Scenarios: Suicide bombers attack Russia

MOSCOW (Reuters) - At least 50 people have been killed and more than 100 wounded over the past three days by suicide bombers who detonated explosives on packed Moscow metro trains and near a school in the southern region of Dagestan.

The following is a look at how events may unfold after the attacks.

MORE ATTACKS?

The metro bombing, which killed at least 39 people in the bloodiest attack on Moscow in six years, has raised fears that Islamist militants could carry out a series of attacks on the Russian heartland.

The attack in Dagestan, which killed at least 12 in one of the most turbulent regions of the North Caucasus, underlines the growing Islamist insurgency along Russia's southern flank.

Such attacks in Dagestan have been on the rise over the past year but a follow-up attack outside the North Caucasus or against economic targets such as pipelines could alarm investors and increase pressure on Russian leaders for a show of force.

Russia has increased security at airports, train stations and across the North Caucasus.

ECONOMIC TARGETS?

The rouble initially fell on Monday's bombings but soon recovered while stock and bond markets shook off the news. The bombings in Dagestan had no immediate market impact.

But any attacks on Russia's economic infrastructure -- including gas and oil pipelines or even one of Russia's 10 nuclear power stations -- could spook markets.

Chechen rebels have promised to wage an economic war on Russia with attacks on gas and oil pipelines, as well as power stations, attacks on the electricity grid and factories.

A group known as the "Riyadus-Salikhin Battalion of Martyrs" in August claimed responsibility for a Siberian dam disaster that killed 75 people.

The claim posted on the unofficial Islamist rebel website www.kavkazcenter.com was dismissed by Russian officials.

But a new bombing campaign against the Russian heartland could drive up the risk premiums investors demand for buying Russian assets.

"For portfolio investors, any sharp escalation of attacks could in the medium term result in a widening of discounts to comparable markets across asset classes," Eurasia Group said in a research note sent to clients.

"They could also lead foreign direct investors in Russia to reassess their plans, and/or push investors to require higher rates of return to justify their presence in the Russian market," the group said.

WHO IS RESPONSIBLE?

No group has yet claimed responsibility for the bombings, but Russian authorities blamed female suicide bombers with connections to the North Caucasus for the attacks in Moscow.

Prime Minister Vladimir Putin, who called for the culprits to be scraped "from the bottom of the sewers," said one group could have been behind the bombings in Moscow and Dagestan. He gave no further details.

Chechen rebel leader Doku Umarov, who styles himself the "Emir of the Caucasus Emirate," in February vowed to spill blood in Russian cities.

"Blood will no longer be limited to our (Caucasus) cities and towns. The war is coming to their cities," he said in an interview on the www.kavkazcenter.com site.

A representative of the militant group Umarov leads denied responsibility on Wednesday for the Moscow bombings.

Analysts in Moscow said that if the trail led to the North Caucasus then the Riyadus-Salikhin group, which specializes in suicide attacks, could be behind the attacks.

The group was involved in the Dubrovka Theater siege in Moscow in 2002 and in the 2004 Beslan school hostage crisis, when at least 334 people died, half of them children.

Riyadus-Salikhin was once under the command of Chechen warlord Shamil Basayev, but survived his death in 2006, and is still active. Its command structure is unclear, but some say it reports to Umarov.

CRACKDOWN ON NORTH CAUCASUS REBELS

Putin, who gained power and popularity in 1999 by launching a war to crush Chechen separatists, has told law enforcement agencies to track down and punish those responsible for the attacks.

"We know they're lying low, but it's a matter of honor for law enforcement bodies to scrape them from the bottom of the sewers and into the daylight," Putin said.

After the blasts in Dagestan, Putin said police forces should be strengthened across the North Caucasus and analysts said Putin's tough rhetoric was likely to go down well with most of the Russian electorate.

But many local leaders have cautioned that heavy-handed tactics by law enforcement agencies have driven recruits into the hands of the Islamist insurgents.

President Dmitry Medvedev has mixed warnings that insurgents will be destroyed with milder language about respecting human rights and the need to focus on measures to alleviate dire poverty and other social problems in the North Caucasus.

"All of these must be realized, no matter what, because the key to many of these problems lies in the social and economic sphere," Medvedev said on Wednesday.

POLITICAL FALLOUT

A campaign of attacks could increase calls for a return to the Kremlin by Putin, Russia's most popular politician, who is known in Russia for his uncompromising line on militants.

Many observers say he is already planning to return to the Kremlin in 2012, and he has not rule out running for president in that election.

A renewed focus on the North Caucasus in domestic politics could bolster Putin's standing as Russia's paramount leader while strengthening the position of hardliners in the security forces.

(Writing by Guy Faulconbridge and Conor Humphries; Editing by Dominic Evans)