Kabul  - A suicide bomber detonated his explosives-filled vest inside a ministry in the centre of Kabul Thursday, killing five people and wounding six while four police officers were killed in a roadside blast in southern Afghanistan, officials said.

Security guards at the Ministry of Information and Culture opened fire on the bomber but he managed to enter the building and blow himself up, said a ministry official, who did not want to be named.

Witness Mahmoud Jan said he heard sounds of small-arms fire after the blast.

"Five people - a woman and four men - were killed," said Alishah Ahmadzai, Kabul's deputy police chief.

He also confirmed that the guards opened fire on the bomber. He added that police arrested a man believed to have helped the bomber.

Taliban militants claimed responsibility for the attack in a statement posted on their website and said that three of their fighters stormed the ministry when foreign advisers were meeting with Afghan officials inside.

The statement said one of the fighters, identified only as Naqeebullah, detonated his explosives inside the building while two others fled the area after shooting the guards.

The Taliban statement said six guards were killed, but they did not have any information about the foreign advisers.

The area where the attack occurred, which is packed with stalls and shops, was littered with glass, office equipment and mangled pieces of the ministry's front door.

In another incident, four Afghan police were killed and one was wounded Thursday when their vehicle was blown up by a roadside bomb in the Dand district of the southern province of Kandahar, Matiullah Qaneh, the provincial police chief, said.

He blamed "enemies of Afghanistan" for the attack, a term often used by Afghan officials to describe Taliban militants, who were ousted from power in late 2001.

Meanwhile, President Hamid Karzai, who is attending a world economic forum in Turkey, condemned Thursday's bombing in Kabul, his office said in a statement.

"The continued terrorist attacks by the enemies of Afghanistan is a clear sign of their profound hostility with the progress, peace and stability of our country," Karzai said.

Taliban militants, have recently heavily relied on the use of suicide and roadside attacks as part of their insurgency against the Afghan government and about 70,000 international troops in the country.

Taliban militants have increased their attacks inside Kabul, the seat of the Western-backed government, since the beginning of this year.

Among numerous attacks in the city, several militants wearing suicide vests attacked the luxury Kabul Serena Hotel in January. The attack killed several people, including a US and a Norwegian citizen.

About 50 people were killed and more than 100 were wounded in a suicide attack on the Indian embassy in Kabul in July. Three Indian nationals, including two diplomats, were among those killed. (dpa)