Taliban insurgents killed seven Afghan policemen in an attack on a police post and a separate suicide bomb blast on Wednesday, officials and witnesses said.

Five police were killed when Taliban insurgents attacked their post in the eastern province of Kunar, near the border with Pakistan, Abdul Saboor Allahyar, a senior provincial police officer said.

"After the attack, a clash erupted in which 13 Taliban were also killed," Esmatullah, a border force commander, told reporters.

In a separate incident, a suicide bomber attacked a police compound in the Girishk district of the southern province of Helmand, the district police chief said.

Police opened fire on the bomber setting off his explosives belt as he tried to enter the compound, but two officers were killed in the blast, Girishk police chief Khan Mohammad Shuja told Reuters.

Violence has increased in Afghanistan since 2006, the bloodiest period since U.S.-led and Afghan forces toppled the Taliban in 2001. Nearly 12,000 people including more than 330 foreign troops, have been killed in the last two years.

The al Qaeda-backed Taliban have vowed to topple the Afghan government and drive out the foreign troops who back it.

Police have arrested a man they said organised suicide attacks in the southern province of Kandahar, the Interior Ministry said on Wednesday.