Four British soldiers were killed in a vehicle crash in southern Afghanistan, the ministry of defence said, only days after Britain passed the grim milestone of 300 deaths.

Three soldiers from 1st Battalion The Mercian Regiment and one from 1st Battalion The Yorkshire Regiment died in the accident near Gereshk in Helmand province on Wednesday evening, the ministry said.

"They were part of a team that was travelling to assist in an incident at a nearby checkpoint when they were killed in a vehicle incident," said Lieutenant Colonel James Carr-Smith, spokesman for Task Force Helmand.

Earlier the NATO-run International Security Assistance Force (ISAF) in Kabul had announced the death of four NATO troops in an accident, but did not give their nationalities.

The deaths made June the deadliest single month for US-led foreign forces in the nearly nine-year conflict.

They took the British death toll since the 2001 US-led invasion of Afghanistan to 307, three days after it passed the landmark of 300 dead on Monday.

- AFP