"The operation will continue till the objective of clearing the area of militants is achieved.

"Also, 28 civilians died in the violence, which is very unfortunate."

'Bombs defused'

Bodla said the army was forced to act in Swat because the fighters were "attacking the security forces, setting ablaze schools and harming the local population. We defused eight bombs on Saturday alone. 

Five girls' schools in the region were set on fire early on Sunday morning in another assault.

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Victims of the Swat Valley fighting

Officials had announced on Saturday that pro-Taliban groups had destroyed 61 schools serving around 17,000 children in the valley.

Bodla said on Monday that "the army showed restraint following the May 21 peace deal between militants and the provincial government. But the militants violated the agreement consistently".

Separately on Monday, in the tribal region of South Waziristan bordering Afghanistan, eight soldiers were wounded when a roadside bomb hit their convoy, security officials said.

The bomb was planted on the road at Tanai, some 20km east of Wana, the main town in the troubled district, they said.

Clash at Matta

A Pakistani military statement issued on Sunday had announced the deaths of at least 15 fighters and one soldier in clashes in Swat's Matta district.

The fighting erupted after pro-Taliban fighters in the area claimed responsibility for a bomb blast the day before that killed six policemen and three paramilitary soldiers.

Officials said the remote-controlled bomb, which also wounded five policemen, was set off as the group returned to base after a search operation in the Kabal district.

"We carried out the bombing which killed the policemen," Muslim Khan, a spokesman for one of the largest pro-Taliban groups in Swat, said in telephone calls to reporters.

He said the fighters were justified in launching such attacks because security forces were killing them.

Threat of attacks

The fighters have threatened to launch suicide attacks across the country if the military failed to halt their operations against followers of Maulana Fazlullah, the Pakistan Taliban's leader in Swat who carries a four million rupee ($56,000) bounty on his head.

Hundreds of residents have fled their homes in Swat in the wake of violent clashes, witnesses said.

The mountainous region was a thriving tourist resort until last year, when Fazlullah launched an armed campaign to enforce sharia law in the region.

Under the May peace deal, the government agreed to gradually pull out troops and introduce an Islamic justice system. In exchange, pro-Taliban fighters said they would halt attacks and surrender arms.