Farmers 'killed'

The casualties were all farmers who had gathered in the area to receive free seeds from the government as part of a program to encourage them not to plant opium poppy, Daoud Ahmadi, a spokesman for the provincial government, said.

In depth

  Holbrooke on 'Operation Moshtarak'
  Operation Moshtarak at a glance
  Video: Kandahar's sitting ducks
  Video: Forces 'positive' on Afghan assault
  Video: Afghanistan's influential elders
  Video: Taliban second in command captured
  Focus: To win over Afghans, US must listen
  Timeline: Afghanistan in crisis

Lashkar Gah is near Marjah in Helmand province, the focus of a major Nato-led offensive against the Taliban.

Thousands of Nato and Afghan troops have launched a massive offensive in southern Afghanistan - the largest the country has seen since the 2001 US-led invasion.

A major offensive in Kandahar, once a Taliban stronghold, would follow the current military operation in neighbouring Helmand province,which appears to have largely pushed back the Taliban and given the government a chance to take control.

Marjah is also thought to be the hub of the Taliban-controlled opium trade - which provides them with most of their funding.

The Afghan defence ministry has said the anti-Taliban push will be led by Afghan security forces as part of plans to hand over military and police responsibility to the Western-backed government.

The US and Nato have about 113,000 troops fighting in Afghanistan, with another 40,000 being deployed in the coming months.