Taliban-related militancy surged with the onset of spring in the war-plagued Afghanistan as more than 10 people including four American soldiers have been killed over the last two weeks.

A deadly roadside bomb attack killed four US soldiers in southeastern Logar province on Saturday and a remote controlled bomb left four injured including a Canadian diplomat on Sunday.

Mullah Abdul Latif Hakimi, purported Taliban's spokesman who claimed responsibility for the violent attacks, asserted that the remnants of the former fundamentalist regime would intensify their assault against the US-dominated foreign forces.

In separate violent attacks by suspected Taliban operatives, two American soldiers were wounded in southern Uruzgan province while four Afghan policemen were killed in the western Farah province respectively on Tuesday. The incidents were followed by two rocket attacks on Herat airport in west Afghanistan where the US forces is stationed.

A car bomb attack coincided with the US First Lady's visit to Kabul left the driver killed in the eastern city of Jalalabad, provincial capital of Nangarhar on Wednesday.

In the meantime, the Afghan government downplayed Taliban's claim for responsibility for conducting attacks or being able to target government or US-led foreign military personnel.

"They are hiding in caves with radios and satellite phones. Whenever they hear of an incident of mine explosion left over from the past, they boastingly claim responsibility for that and show to the world that they are alive," Karzai's spokesman Jawed Ludin said while commenting on Taliban's ability to cause security problem.

Taliban's elusive leader Mullah Mohammad Omar, whose regime was toppled under a US-led military invasion in late 2001, in a recent statement vowed to intensify attacks on the US-led foreign forces when the weather gets warm.

Militants' activities were considerably dropped off in Afghanistan's harshest winter as few security incidents have been reported over the past two months, of which US military termed as a setback to Taliban, saying the outfit has lost capability to create trouble.

Apparently the Taliban remnants are mounting new wave of attacks amid government-initiated reconciliation policy and peace talks with the hardline militia, during which Afghan authorities as well as US ambassador to Afghanistan Zalmay Khalilzad announced amnesty for most of Taliban operatives, trying to persuade them lay down their arms and resume normal live in the communities.

However, Taliban's chief who has escaped the US biggest man hunt operation in the region had termed the offer as a ploy to split his loyalists and called upon his followers to speed up the attacks in the future.