Militants in Pakistan sever Afghan supply link

(Adds details, violence in Swat Valley)

PESHAWAR, Pakistan, Feb 3 (Reuters) - Suspected militants blew up a bridge in northwestern Pakistan's Khyber Pass on Tuesday, cutting the main route for supplies bound for Western forces in Afghanistan, a government official said.

Separately, security forces killed at least 35 Taliban insurgents and wounded many in an attack on Monday night in the Swat Valley, northeast of the Kyber Pass, a military spokesman said.

Militants in northwestern Pakistan stepped up attacks on the road through the Khyber Pass, a crucial route into landlocked Afghanistan, last year in an attempt to deprive international forces fighting the Taliban of supplies trucked in from Pakistan.

The 30-metre (100-foot) iron bridge was blown up after midnight and administration officials said all traffic along the route was suspended.

"Militants blew up the bridge and it's going to take some time to fix it," said government official Rahat Gul. He declined to estimate how long it might take.

Militant attacks over recent months have disrupted supplies but the route had only been briefly closed twice since September.

There are two routes through Pakistan into Afghanistan, one through the Khyber Pass, to the border town of Torkham and on to Kabul.

The other runs through Pakistan's Baluchistan province to the border town of Chaman and on to the southern Afghan city of Kandahar.

The U.S. Defense Department says the U.S. military sends 75 percent of supplies for the Afghan war through or over Pakistan, including 40 percent of the fuel for its troops.

In the Swat Valley, security forces pounded militants with artillery as they gathered to launch an attack, killing at least 35 of them, an officer in the military's information department said.

"We opened fire with artillery and mortars on credible information that a group of militants had gathered and was planning an attack in the dark," the officer said.

There was no independent verification of the casualty estimate.

The scenic Swat valley, only 130 km (80 miles) northwest of the capital, Islamabad, and not on the Afghan border, was until recently one of Pakistan's prime tourist destinations.

Now the valley is on the front line of the country's struggle against Islamist militancy and has become a test of the government's resolve to check the spread of the Taliban. (Reporting by Ibrahim Shinwari and Junaid Khan; Editing by Robert Birsel and Jerry Norton)