A heavily-armed Afghan highway patrol was on the scene within minutes and managed to push back the Taliban fighters after an exchange of fire.

"We were manning a checkpoint when we heard an explosion," Naweb Khan, an Afghan police officer, said.

"There was strong resistance from the enemy when we got here. But they soon fled from the area [and] we defeated them."

Change of strategy

So far attacks on supply convoys have had a limited impact on American and Nato troops but the Taliban says that will soon change.

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Convoys in Taliban sights

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"We want to show them they are not all-powerful and the mujahadin of Afghanistan can carry out attacks on our enemies in any part of the country," the spokesman said.

Most convoy attacks have previously taken place in Pakistan before they cross the border.

"The fact they launched a successful operation on the stretch of highway between Kabul and Jalalabad is what makes this important," Al Jazeera's David Chater, reporting from the scene in Aziz Khan Kaly, said.

"The fighters also had clear intelligence about which vehicles were carrying Nato supplies. Something like 600 lorries make this journey every day."

The supply route weaves through steep Afghan mountain passes, offering ideal territory for ambushes.

In view of the heightened risk, coalition forces are already discussing new supply routes from Russia, and even Iran, Al Jazeera's correspondent said.