No Nato troops were hurt in Sunday's blast, the officer said.

On Saturday, Afghan and US-led forces launched a large military operation against the Taliban in five Afghan provinces, the US military said.

About 4,000 Afghan police and 3,000 US-led soldiers were involved in the operation, a statement from the US military said.

The statement said the goal of the operation, named Mountain Fury, was also to assist with economic growth and community development.

The announcement came as 10 people died in two attacks in Afghanistan on Saturday.

Around 60 Taliban fighters attacked a police checkpoint in the south of the country, sparking a battle that left four fighters and three security guards at the checkpoint dead, police said.

Three Afghan security contractors were also killed when a remote controlled bomb exploded on a road south of Kabul, police said.

Nato operation

The 7,000 troops will concentrate their fight on the central and eastern provinces of Paktia, Khost, Ghazni, Paktya and Logar, the US military statement said.

The operation comes as Nato-led troops in the south press ahead with their own anti-Taliban push, which they claim has killed hundreds of militants in the last two weeks.

"Mountain Fury has been ongoing for several weeks in 'shaping operations' designed to improve security for the Afghan people and separate Taliban extremists from the population," according to the statement.

The US military did not say when exactly the operation started, but said the "manoeuvre stage" was launched early on Saturday.