British forces killed a Taliban leader in southern Afghanistan, UK and Afghan officials said Tuesday, in what they claimed was a major victory against the insurgency there. Mullah Mansur was killed in a strike by helicopters in Helmand province, the British defense ministry said. Helmand government spokesman Daoud Ahmadi said Mansur was the aviation minister in the Taliban regime that was ousted by the US-led invasion in 2001. British military spokesman Lt. Col Nick Richardson said Mansur was "one of the most dangerous men in Helmand." "The attacks he helped plan and execute have probably killed or wounded hundreds of people, and most of them have been either Afghan civilians or police," he said, adding his death on Monday was a "serious blow" to the insurgency. Helmand is a stronghold of Taliban militants, who control wide swaths of territory in the province. It is also the world's largest opium poppy growing region, a major source of funds for the insurgency. Insurgent attacks in Afghanistan are running at record levels, and the central government has little authority outside the capital, Kabul, despite the presence of more than 40,000 foreign troops. President Barack Obama has ordered an extra 21,000 troops to the country to turn the deteriorating situation around. Most are heading to the south. "This year and next will be the two most important years here since 2001 and 2002," Gen. David McKiernan, the outgoing top general in Afghanistan, said in a final speech at US and NATO command in Kabul. Earlier, a suicide bomber killed six Afghan family members, including two children, close to a US military base just outside the capital, authorities said. It was the second bombing near the Bagram base in less than a week. The Ministry of Interior said in a statement that suspected insurgents carried out a suicide bombing against the family while they were traveling in a car. It was unclear why they were targeted. Also Tuesday, Afghan and coalition forces attacked a residential compound in Wardak province, killing six militants, the US military said in a statement. It said the men were connected to a militant commander blamed for multiple attacks.