A US drone fired two missiles on a militant compound in the tribal North Waziristan region of Pakistan Thursday, killing four militants, security officials said.

"Two missiles were fired on a compound located in a forest in Khaisoori town of Mir Ali district," a security official said.

He said four militants were killed and two others were wounded in the attack that targeted the compound and a vehicle parked nearby, which was destroyed in the strike.

The attack was confirmed by two other security officials who spoke on condition of anonymity.

Khaisoori is situated about 40 kilometres (25 miles) east of Miranshah, the main town in North Waziristan.

The missile strikes have reached record levels in the past month, killing more than 150 people since September 3, amid reported US criticisms of Pakistan's efforts to stamp out the Islamist threat in the border region.

Pakistan said earlier that there was "no justification" for the US drone strikes on its soil that are believed lately to have targeted militants plotting attacks on Europe, amid stuttering relations with Washington.

"We believe that (the attacks) are counter-productive and also a violation of our sovereignty," foreign ministry spokesman Abdul Basit told reporters, adding, "we hope that the US will revisit its policy."

Basit said that the strikes would not help efforts to thwart terrorism, as he said they damaged efforts to win hearts and minds in the region, "which is part and parcel of our strategy against militants and terrorists."

Eight people were killed Wednesday in attacks by the pilotless planes against militants in North Waziristan tribal district, security officials said.

The US has launched 27 drone attacks in a new wave since September 3, while more than 1,100 people have died in 143 strikes since the campaign began in August 2008.

Officials in Washington say previous drone strikes have killed a number of high-value targets including former Pakistani Taliban chief Baitullah Mehsud.

Pakistan's ambassador in Washington, Hussein Haqqani, told the BBC that the increase in strikes in North Waziristan came after intelligence agencies uncovered a plot to attack multiple targets in Europe.

The Al-Qaeda plot reportedly targets Britain, France and Germany with a wave of commando-style attacks on key landmarks including Paris's Eiffel Tower and Notre Dame Cathedral and Berlin's Brandenburg Gate.