* U.N. Security Council approves military action
* Gaddafi says no mercy for Benghazi
* Fighting rages along road to rebel stronghold
* U.S. official says pro-Gaddafi forces made big strides
(Adds Obama telephone calls, detail)
By Maria Golovnina and Patrick Worsnip
TRIPOLI/UNITED NATIONS, March 18 The United
Nations authorised military strikes to curb Libyan leader
Muammar Gaddafi, hours after he threatened to storm the rebel
bastion of Benghazi overnight, showing "no mercy, no pity".
"We will come. House by house, room by room," Gaddafi said
in a radio address to the eastern city late on Thursday.
Al Jazeera television showed thousands of people listening
to the speech in a central Benghazi square, then erupting in
celebration after the U.N. vote, waving anti-Gaddafi tricolours
and chanting defiance of the man who has ruled for four decades.
Fireworks burst over the city and gunfire rang out.
The U.N. Security Council, meeting in emergency session,
passed a resolution endorsing a no-fly zone to halt government
troops now around 100 km (60 miles) from Benghazi. It also
authorised "all necessary measures" -- code for military action
-- to protect civilians against Gaddafi's forces.
But time was clearly running short for the city that has
been the heart of Libya's month-old revolution.
French diplomatic sources said military action could follow
within hours, and could include France, Britain and possibly the
United States and one or more Arab states; but a U.S. military
official said no immediate U.S. action was expected.
More on Middle East unrest: [nTOPMEAST] [nLDE71O2CH]
Western forces in region link.reuters.com/jen38r
Latest graphic: r.reuters.com/nym77r
Interactive factbox link.reuters.com/puk87r
Graphic on air bases link.reuters.com/zyk48r
Graphic on missile defences link.reuters.com/wem48r
Graphic on no-fly zone link.reuters.com/wub68r
While other countries or NATO may play roles in military
action, U.S. officials expect the United States with its
extensive air and sea forces would do the heavy lifting in a
campaign that may include airstrikes on tanks and artillery.
Gaddafi warned Benghazi residents that only those who lay
down their arms before his advancing troops would be spared the
vengeance awaiting 'rats and dogs'.
"It's over. The issue has been decided," Gaddafi said. "We
are coming tonight...We will find you in your closets.
"We will have no mercy and no pity."
Residents said the Libyan air force unleashed three air
raids on the city of 670,000 on Thursday and there has been
fierce fighting along the Mediterranean coastal highway.
Ten of the Council's 15 member states voted in favour of the
resolution, with Russia, China and Germany among the five that
abstained. There were no votes against the resolution, which was
co-sponsored by France, Britain, Lebanon and the United States.
Apart from military action, it expands sanctions against
Gaddafi and associates imposed last month. Among firms whose
assets it orders frozen are the Libyan National Oil Corp and the
U.S. President Barack Obama called British and French
counterparts David Cameron and Nicolas Sarkozy and agreed to
coordinate closely on their next steps.
Libya said the resolution, which also demands a ceasefire by
government forces, was not worth the paper it was written on.
Rebel National Council head Mustafa Abdel Jalil told Al
Jazeera television air strikes, beyond the no-fly zone, were
essential to stop Gaddafi.
"We stand on firm ground. We will not be intimidated by
these lies and claims... We will not settle for anything but
liberation from this regime."
It was unclear if Gaddafi's threat to seize the city in the
night was anything more than bluster. But at the very least it
increased the sense that a decisive moment had arrived in an
uprising that only months ago had seemed inconceivable.
Some in the Arab world sense a Gaddafi victory could turn
the tide in the region, weakening pro-democracy movements that
have unseated autocrats in Tunisia and Egypt and raised mass
protests in Bahrain, Yemen and elsewhere.
Gaddafi's Defence Ministry warned of swift retaliation, even
beyond Libyan frontiers, to any military action against the
"Any foreign military act against Libya will expose all air
and maritime traffic in the Mediterranean Sea to danger and
civilian and military (facilities) will become targets of
Libya's counter-attack," the ministry said in a statement.
John Drake, senior risk consultant at UK-based consultancy
AKE said he did not think Gaddafi would strike against oil
facilities or oil companies. "He would be hurting himself."
"We don't think they have the capability to impose a no-fly
zone over the whole country immediately, although they could try
to impose one over Benghazi and maybe also Tripoli," he said.
Proposals for action could include no-fly and no-drive
zones, a maritime exclusion zone, jamming army communications
and intelligence help. Air strikes would almost certainly be
launched to knock out Libyan radar and air defences.
An Italian government source told Reuters Italy was ready to
make its military bases available. The airbase at Sigonella in
Sicily, which provides logistical support for the United States
Sixth Fleet, is one of the closest NATO bases to Libya.
Past no-fly zones have had mixed success.
The U.N. imposed a no-fly zone over Bosnia in the 1990s,
although some analysts say the measure did nothing to stop
massacres such as the 1995 slaughter of more than 8,000 Muslim
men and boys in the town of Srebrenica.
Former British foreign minister David Owen saw the vote as
reflecting a serious division in NATO and the EU, with Germany
abstaining and declaring that the venture carried "considerable
dangers and risks".
"It's very late for this no-fly zone," Owen said. "Gaddafi's
forces are very close to Benghazi and may now push on."
The resolution followed a sharp shift in tone by the United
States, which had resisted calls to military action. Diplomats
said Washington's change of mind was influenced by an appeal to
action by the Arab league and the prospect of a Gaddafi
government flush with oil wealth fomenting unrest in the region.
"Mission creep" poses a serious danger. Western powers,
chastened by protracted wars in two other Muslim countries,
Afghanistan and Iraq, would be wary of getting drawn into any
ground action in Libya.
Rebels have retreated over the last two weeks as Gaddafi,
dubbed the 'mad dog of the Middle East' by president Ronald
Reagan in 1986, has brought air power and heavy armour to bear.
Residential areas of Ajdabiyah, a strategic town on the
coast road to Benghazi, were the scene of heavy fighting on
Thursday and around 30 people were killed, Al Arabiya reported.
On the approaches to Ajdabiyah, burned-out cars lay by the
roadside while Libyan government forces showed the foreign media
artillery, tanks and mobile rocket launchers -- much heavier
weapons than those used by the rebels.
In Libya's third city, Misrata, about 200 km (130 miles)
east of Tripoli, rebels and residents said they were preparing
for a new attack by Libyan troops, who had shelled the coastal
city overnight. A government spokesman said Gaddafi's forces
expected to be in control of Misrata by Friday morning.
(Additional reporting by a Reuters reporter in Benghazi,
Michael Georgy in Tripoli, Mariam Karouny and Tarek Amara in
Tunisia, Louis Charbonneau and Patrick Worsnip at the United
Nations, John Irish in Paris; Writing by Ralph Boulton; Editing
by Michael Roddy)