KABUL: A bomb hidden in a parked motorcycle ripped through a crowded Afghan market in southern Helmand province on Tuesday, killing at least three people, as Nato reported that US special forces had come under attack the previous day north of Kabul.

The attack on the Americans was the second that targeted international troops in Afghanistan on Monday. According to Nato spokesman Maj. Bryan Woods, a suicide bomber rammed his vehicle into a US Special Operation Forces' convoy as it was returning to base after clearing land mines north of the Afghan capital, Kabul.

There were no casualties in that attack, which occurred in Kapisa province, said Woods.

He said as the bomber targeted the US convoy, insurgents simultaneously started firing upon it. Qais Qadri, spokesman for the Kapisa governor, said one civilian was killed in the attack but Woods could not confirm the civilian death, saying only that the special forces returned safely to their base ''after engaging the enemy.''

Earlier on Monday, a truck bomb hit the entrance of a Georgian outpost in the Musa Qala district in Helmand, one of the most volatile regions of Afghanistan, killing three service members from the former Soviet republic.

Georgian soldiers are under Nato's command. And on Tuesday, the motorcycle bomb hit a market in Safar, a village 70 kilometers (42 miles) from the district center of Garamser in Helmand, said Omer Zawak, the spokesman for the provincial governor.

Three people were killed and seven were wounded in the blast, said Zawak, fearing the toll would rise because Tuesday is the day local residents hold their weekly bazaar.

Four children were among the wounded and two of them were reported in critical condition, said police spokesman, Shah Mahmood Hashna.

Zawak said that in Monday's attack on Georgian soldiers, several troops were also wounded.

The deaths of the three Georgian troops brought the number of soldiers from the former Soviet republic killed in Afghanistan to 22.

Georgia has about 1,600 troops in Afghanistan, the largest non-Nato contingent there. Georgian soldiers are under Nato's command. So far this month, 12 international service members have been killed in Afghanistan, according to an Associated Press count. Along with the three Georgians, eight of those were Americans and one was German.