Gunbattles and a suicide bombing killed 12 militants and six policemen across southern Afghanistan. Insurgents also brought their fight to the capital, targeting NATO patrols with bicycle-rigged bombs that wounded four alliance soldiers.

The bloodshed on Monday came amid Afghanistan's deadliest surge in violence since U.S.-led forces toppled the Taliban regime in late 2001 for harboring Usama bin Laden and deployed tens of thousands of soldiers to this war-wracked country.

Southern and eastern provinces have witnessed most of the ambushes, suicide bombings and military operations since early this year. But Monday's bombing in the capital, which is patrolled by thousands of NATO-led troops, might signal a new phase in insurgent plans to attack targets in Kabul, which has so far been largely spared from violence.

CountryWatch: Afghanistan

In the mountains of southern Helmand province, a clash left 11 suspected Taliban and two policeman dead, said deputy provincial governor Amir Mohammed Akhunzada. One policeman was wounded and three militants were arrested.

Insurgents killed four more police officers who were racing to help a local official ambushed by militants in the southeastern Ghazni province, said Abdul Ali Fakuri, spokesman for the provincial governor.

The militants stole one police vehicle and the weapons of the slain policemen during the clash in the Giro district, Fakuri said.

Other Afghan and U.S.-led coalition forces rescued the district government chief, who was unharmed, Fakuri said.

In neighboring Paktika province, a suicide car bomber in a taxi targeted Afghan troops shopping in a bazaar, wounding six soldiers and one civilian, a provincial spokesman said. The bomber drove to within 40 meters of the soldiers in Barmal district before his vehicle exploded.

A would-be suicide bomber on a bicycle also attacked a police pickup truck in central Logar province, wounding only himself and causing no other casualties, said the provincial police chief. The police vehicle was damaged and the militant arrested.

In Kabul, a bomb rigged to a bicycle exploded as a NATO patrol passed, slightly wounding four French soldiers, France's Defense Ministry said. Three civilians were also wounded, officials said. A second bomb found at scene in the northern neighborhood of Khayrkhana was disarmed.

Another bomb-rigged bicycle blew up as a NATO vehicle passed on a main road near a U.N. office in the capital, an Interior Ministry spokesman said. The bomb exploded prematurely and caused no damage or casualties, he said, adding a suspect had been arrested.