DERA ISMAIL KHAN, Pakistan (Reuters) - A U.S. drone strike killed at least six suspected militants in northwest Pakistan on Sunday, four intelligence officials said, as Pakistani officials debated plans to strengthen a crackdown on the Taliban insurgency.

The strike hit two compounds in Lawara Mandi, North Waziristan, near the border with Afghanistan, the officials said. They said between six and nine suspected militants had been killed.

The strike comes as Pakistan seeks to intensify a crackdown on Taliban insurgents who massacred 132 school children last month, the worst single militant attack in the country's history.

Legislators are due to vote on Tuesday on a constitutional amendment allowing militant suspects to be tried by military courts. Many say the country's civilian courts are too intimidated and corrupt to properly try militants.

Pakistan often publicly denounces drone strikes as an infringement of its sovereignty. Drone strikes stopped for the first six months of 2014 while Pakistan pursued peace talks with the Taliban, but resumed days before Pakistan's latest anti-Taliban offensive started last June.

(Additional reporting by Haji Mujtaba in Bannu; Writing by Katharine Houreld; Editing by Michael Perry)