A blast ripped through a NATO convoy in eastern Afghanistan on Tuesday, killing three troops in an attack claimed by the Taliban, as a policeman died in a suicide bombing similar to scores by the group.
The deaths took to five the number of International Security Assistance Force (ISAF) soldiers killed since the weekend in a series of engagements -- some of them the most intense in weeks -- that have left nearly 140 rebels dead.
The soldiers were on patrol in the mountainous eastern province of Nuristan, bordering Pakistan, when a roadside bomb struck their vehicle, ISAF said in a statement. Two soldiers were killed and two wounded, one of whom died later.
The nationalities of the troops were not released by the 37-country ISAF, which says it is the responsibility of the troops' home nations. Most of the soldiers in eastern Afghanistan are from the United States.
More than 115 foreign soldiers have been killed in action in Afghanistan so far this year, up from around 75 last year.
A purported spokesman for the Taliban movement said it had carried out the attack with a remote-controlled device.
Near-daily roadside bombings are a key feature of the spiralling Taliban insurgency launched after they were forced out of government in 2001.
A suicide bombing in southern Ghazni province's Taliban-dominated Ander district also bore the hallmarks of the group, which has claimed responsibility for scores of such attacks this year.
A man detonated explosives strapped to his body just steps away from a police patrol, interior ministry spokesman Zemarai Bashary said.
"One of our policemen was martyred and another was wounded," he told AFP.
The Afghan intelligence agency announced meanwhile that it was holding three would-be suicide bombers whom it said had been sent from militant outfits based in Pakistan to carry out attacks in Kabul.
The city was badly shaken by a spate of seven suicide attacks over as many weeks in September and October that killed nearly 40 people, including foreign soldiers.
ISAF said this month there had been 91 suicide attacks nation-wide this year. The attacks killed 155 civilians, 40 members of the Afghan security forces, six government officials and 14 foreign troops, it said.
The Taliban insurgency has peaked this year with the rebels taking on security forces in sophisticated conventional-style warfare.
They have however suffered heavy losses against the superior might of the foreign forces, with ISAF commanders saying their defeats have led them to revert to relying on guerrilla-style tactics.
The rebels have been pounded in three major engagements since Saturday.
In the first, Afghan and ISAF troops killed up to 70 insurgents in a battle involving attack helicopters and air support in Uruzgan province in the south.
On Monday the force killed 55 insurgents in an intense six-hour battle in the neighbouring province of Zabul.
Later the same day, ISAF warplanes killed 12 insurgents in the southern province of Kandahar after the fighters were spotted moving into position on the roof of a compound, a statement said Tuesday.
The force also lost two soldiers -- one in Zabul and one in Uruzgan -- on top of the two killed on Tuesday.
Extremist networks have also come under pressure just across the border in Pakistan, with Pakistani helicopter gunships destroying a school allegedly used as an al Qaeda-linked training camp on Monday.
The military said up to 80 suspected militants were killed in the airstrike in the troubled Bajaur tribal agency, but local leaders insisted that most of the dead were teenage students.
The strike was one of the biggest ever in Pakistan's frontier region.