KANDAHAR (AFP) -- Two British soldiers killed when rebels attacked their base in southern Afghanistan in a district where 12 Taliban also died in a battle, the Afghan and British military said Sunday.

Rebels attacked the base in Helmand province's Sangin district with small arms and rocket-propelled grenade fire, British military spokesman Lieutenant Rob Hunt told AFP.

The base had been under attack for three nights, said another spokesman, Captain Drew Gibson.

"The first two it was fairly minor -- last night was a fairly concentrated attack," he said from Helmand.

They were the fourth and fifth British soldiers to be killed in Afghanistan in the last three weeks and since a new deployment of British troops began arriving in Helmand in April, he said.

Two others were killed on June 27, also in Sangin.

Gibson said the force had not yet determined how many of the attackers died.

Afghan police announced meanwhile that 12 Taliban were killed in the same district late Saturday after the Afghan army, police and coalition came under attack.

It was not immediately clear if it was the same incident in which the British soldiers lost their lives.

"Twelve Taliban bodies were left at the site after two hours of fighting with joint forces," Helmand police chief Mohammad Nabi Mullah Khail told AFP.

Britain has about 2,000 troops in Helmand, one of the most restive provinces in the country, to help the government extend its authority and bring Taliban-linked rebels and drugs lords under control.