A suicide bomber on a motorcycle attacked a NATO convoy in Afghanistan's southern province of Kandahar Friday, wounding seven people including four soldiers, an official said.

"A suicide attacker rammed his explosives-laden motorcycle into a convoy of NATO troops in Dand district injuring four foreign soldiers, one policeman, one translator and one civilian," provincial governor Toryalai Weesa told AFP.

A spokesman for NATO'S International Security Assistance Force (ISAF) confirmed the attack, but would not give details of any wounded soldiers, saying only that none had been killed.

The attack bore the hallmarks of Taliban insurgents, who on Monday targeted NATO troops in a suicide car bombing at an airport in eastern Afghanistan, killing nine people but no foreign soldiers.

The Taliban said that attack was in revenge for the burning of Korans at a US military base at Bagram north of Kabul, an incident that ignited days of violent anti-US protests and led to an apology by US President Barack Obama.

The only NATO soldiers reported killed in Afghanistan in the 10 days since the demonstrations erupted have died at the hands of Afghan colleagues.

Two Americans were killed at a military outpost in Kandahar Thursday, taking the number of Americans killed by Afghan associates to six since outbreak of the protests.

NATO withdrew all its advisors from Afghan government ministries after two American officers were shot and killed inside the interior ministry last Saturday, apparently by an Afghan colleague.

Two days earlier, two American troops were killed by an Afghan soldier who turned his weapon on them as demonstrators approached their base in the east of the country.

Of the 60 NATO troops killed so far this year 18 percent -- almost one in five -- have died at the hands of Afghan colleagues, including four French and an Albanian, as well as the six Americans.

The US-led NATO force has 130,000 troops fighting the Taliban, which has led an insurgency against the Western-backed Kabul government since being toppled from power in 2001.

All combat troops are due to be pulled out by the end of 2014, but the increasing number of attacks on foreign soldiers by their allies in the Afghan security forces has led to calls for an accelerated withdrawal.

Obama has said, however, that he believes the United States can stick to its Afghan drawdown timetable.

"I feel confident that we can stay on a path that by the end of 2014, our troops will be out and will not be in a combat role and Afghans will have capacity, just as Iraqis, to secure their own country," Obama said.

Some 40 people were killed in six days of demonstrations over the Koran burning, as protesters targeted Western bases, plunging relations between foreign forces and their Afghan allies to an all time low.