A woman and two children were among 18 people killed by US-led troops during an operation against fighters in southern Afghanistan, the US military has said.

The deaths came after the soldiers "used a single grenade" on a building while raiding compounds in Helmand province, according to a statement from US military officials on Monday.

US-led forces say they came under fire during the operation from fighters barricaded inside the building and returned fire before bombing it with a grenade.

The bodies of the woman and children were recovered from the collapsed building in Garmser district on Sunday.

Another woman wounded during the battle was taken to a medical facility for treatment.

The bodies of fighters and weapons were also retrieved, according to the US military.

Rising violence

The incident comes after the United Nations reported around 300 civilians have been killed in operations by Afghan and US-led troops targeted at Taliban fighters.

Civilian casualties have incited resentment and demonstrations against US and NATO forces in Afghanistan.

Hamid Karzai, Afghanistan's president, has repeatedly warned US-led forces operating in the country that his government risks losing support in the country because of the high number of civilian casualties.

A provincial police official said on Monday that four Afghan policemen and two others had been wounded by Taliban fighters the previous night in an attack on a police checkpoint in the city of Ghazni, southwest of Kabul.

Afghanistan has seen a high rise in violence in the last two years with as many as 7,000 people dead during the period of clashes.

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