ISLAMABAD: Pakistan's huge anti-Taliban offensive has displaced around 200,000 people as soldiers suffered their deadliest 24 hours since the assault began, the military said Monday.

Pakistan has claimed a string of successes and has vowed to crush Tehreek-e-Taliban Pakistan (TTP) in South Waziristan, pressing its most ambitious battle yet in a tribal area infested with Al-Qaeda-linked rebels.

But in growing signs that Taliban fighters are seeking to widen the conflict across the vast tribal belt and hobble the offensive, heavily armed insurgents killed five Pakistani troops in surprise raids further north.

Although aid workers have no access to South Waziristan, they have expressed increasing concern about the toll on civilians and an army spokesman told AFP that around 200,000 people have fled their homes in the area since August.

"As of today, 26,165 families have been registered," Colonel Waseem Shahid, spokesman for the army's special support group, told AFP.

He said the army uses a working average of eight members to each family.

Tensions have soared between the incoming families and locals who consider Mehsuds, clansmen of the TTP leader Hakimullah Mehsud, a security threat.

The Red Cross warned last week that relief workers were being kept out of South Waziristan and that the civilian toll is believed to be mounting.

A UN spokeswoman said that half the people were displaced during the past two weeks, bringing to 182,200 the number registered since before end-August.

More than 150 kilometres (94 miles) further north, Taliban armed with rockets and guns stormed a military check post in Bajaur, killing four soldiers in a surprise night-time assault, security and government officials said.

"First they lobbed several rockets and then approached the post and opened fire with automatic weapons," local administration official Ghulam Saidullah told AFP by telephone.

A Pakistan military helicopter crashed in the same area late Saturday, killing six troops after a routine supply mission.

Although the military blamed a technical fault for the crash, the Taliban chief in Bajaur, Maulvi Faqir Mohammad, claimed in a telephone call to AFP from an unknown location that his fighters shot down the aircraft.

Taliban militants also attacked a security post in Hangu, another district northwest of South Waziristan, in which one soldier was killed and three wounded late Sunday, a senior military official said.

Officials said the Taliban had stepped up attacks on check posts in Bajaur, which like South Waziristan is part of Pakistan's largely autonomous tribal belt on the Afghan border considered a sanctuary for Taliban and Al-Qaeda-linked militants plotting attacks on the West and within Pakistan.

"The move is to divert the military's attention from South Waziristan," said administration official Jamil Khan.

The deaths in Bajaur and Hangu, coupled to the killing of six soldiers in South Waziristan brought to 11 the number of troops killed in the deadliest 24 hours for the military since the assault began 10 days ago.

On Monday, the military reported fighting on the advance towards Taliban stronghold Sararogha after claiming its first major success in capturing Kotkai, the TTP chief's hometown.

In the fight to secure Ghalai village, on the road from Kotkai to Sararogha, six soldiers and 10 militants were killed, bringing to 197 the number of militants and to 30 the number of troops killed so far, the military said.

None of the information provided by the army is possible to verify with communication lines down and access banned to journalists and aid workers.

Pakistan sent 30,000 troops into action against an estimated 10,000 Taliban fighters in South Waziristan after a series of major attacks in cities that have left nearly 200 people dead so far this month.

The nuclear-armed nation is on the frontline of the US-led war against Islamist extremists and the Taliban in neighbouring Afghanistan with two years of bombings killing more than 2,280 people.