PESHAWAR, Feb 4- Taliban militants kidnapped 30 Pakistani policemen after a punishing day-long siege, in an embarrassing blow Wednesday for the army battling to win back control of the Swat valley.
The abduction, carried out at night when police and army reinforcements had suspended efforts to break the siege, underscores the huge challenges facing the security services.
Despite a wave of government offensives, the military has failed to impose its authority on the valley, a scenic former holiday region near the border with Afghanistan.
Thousands of Taliban besieged a police station in the area of Shamozai on Tuesday. The army was mobilised to rescue the police and break the circle of rebels, security officials said.
Clashes continued throughout the day but as dusk fell, the operation was suspended. Then, overnight, the Taliban broke into the office, kidnapped the officers and blew up the building, said Swat police chief Dilawar Khan.
Khan said the rebels kidnapped 30 policemen.
A Pakistani intelligence official based in the northwest city of Peshawar said that four paramilitary and police officers had been wounded in clashes with Taliban militants at the station.
Until two years ago, Swat was a jewel in the crown of Pakistani tourism, frequented by foreign and local holiday-makers escaping to the mountains for skiing in winter or more refreshing climes in the punishing heat of summer.
But the area descended into chaos in mid-2007 after radical cleric Maulana Fazlullah embarked on a terrifying campaign to enforce a Taliban-style Sharia law, prompting thousands of people to flee.
Pakistan, under massive Western pressure to clamp down on extremists, has stepped up its attempts to wrest back control of the valley.
Thousands of civilians have fled the area, which locals say has fallen to the insurgents.
In a related development, security and intelligence officials said that 50 militants were killed in military operations across the area from late Monday to Tuesday.
The death tolls are impossible to verify independently with the sprawling region effectively sealed off from the outside world.
Analysts believe the military is inadequately equipped to wage a successful counter-insurgency operation against militants who often melt seamlessly into the populace, while civilians are frequent victims of offensives.
US officials say north-western Pakistan has become a haven for Al-Qaeda and Taliban militants who fled there from neighbouring Afghanistan after the 2001 US-led invasion, regrouping and launching attacks on foreign troops across the border.
Meanwhile, northeast from Swat, Taliban rebels torched 10 trucks contracted to ferry goods for NATO troops in Afghanistan after closing a key route across the border by blowing up a bridge.
"Militants sprinkled oil and then fired rockets at a terminal in the border town of Landi Kotal" late Tuesday, said local government official Rahat Gul.
The attack sparked a blaze that gutted eight containers mounted on lorries and badly damaged two others, he said.
Militants blew up the bridge Tuesday, leaving scores of vehicles stranded and suspending traffic between Peshawar and the Torkham border crossing into Afghanistan across the famed Khyber Pass.
Gul said the road was open for light traffic and was expected to reopen for trucks and other heavy vehicles later in the day.
NATO and US-led forces in Afghanistan are hugely dependent on Pakistan for their supplies and equipment, with an estimated 80 percent of it trucked in by land from there.
In Peshawar city itself, police killed eight Taliban militants in a clash Wednesday that also wounded two policemen, security officials said.
UN Secretary General Ban Ki-moon was on Wednesday due to visit Pakistan, where he is expected to announce the launch of a UN probe into the assassination of former premier Benazir Bhutto.
His brief visit later in the day — his first since taking office two years ago — comes two days after gunmen kidnapped a top UN official in southwest Pakistan.
Pakistani officials say talks will focus on the expected formation of a UN commission to investigate the killing of Bhutto, a two-time prime minister who was killed at a campaign rally in December 2007.