Troops backed by helicopter gunships pounded militants in Pakistan's volatile northwest Saturday, killing 37 in retaliation for suicide bombings that have put pressure on the new government, the army said.

Earlier Saturday, a car bombing at a police station killed six officers in Swat, a valley that used to be popular with tourists, and a roadside bomb in the same region wounded one civilian and four others.

The latest clashes follow one of the country's deadliest terrorist attacks ever on Thursday when a twin suicide bombing at a massive weapons factory killed 67 people and wounded more than 100.

The Taliban have claimed responsibility for much of the violence and vowed to continue unless the army ended its fight against militants in remote, rugged regions along the Afghan border.

"We've warned the government that we'd target police if the army did not stop operations against us," Muslim Khan, a spokesman for the militants, told The Associated Press. "But the government has ignored us."

The military said it had engaged in a fierce battle with militants in the Swat valley on Saturday.

Army spokesman Maj. Nasir Ali said 37 militants and two soldiers were killed, but no militants in the area were immediately available to confirm the fighting or casualties on their side.

The violence underscores the many challenges ahead for Pakistan's ruling coalition government since it forced Pervez Musharraf to resign as president earlier this week.

The two main parties, traditional rivals united primarily in their hatred of the former military ruler, dabbled in striking peace deals with insurgents soon after coming to power, something he also had tried.

The peace effort has met only limited success, and the government is back to relying on military operations in an attempt to beat back the militants, who have expanded their reach beyond traditional tribal regions.

In Swat, the car packed with explosives rammed into the police station, killing least six officers and wounding several others, said local police official Mohib Ullahn.

One civilian died in Bari Kot village in a roadside bomb, said Khan, the Taliban spokesman.

A bomb rigged to a bicycle went off near a vehicle carrying Raja Umar Khatab, a senior police investigator in Karachi, wounding four people Saturday, said Wasim Ahmad, the city's police chief.

Khatab, who has played key role in arresting many militants in recent years, was among those hurt, he said.