A Taliban suicide bomber on a motorcycle detonated a blast on Wednesday near the car of a senior Afghan intelligence official in a central Kabul business district, killing four Afghans.

The target of the attack, Kamaluddin, who heads an intelligence department, was among 12 wounded in the attack, the latest in a series of raids by the Islamist rebels, the intelligence office said in a statement.

Earlier a police officer said five of the wounded were intelligence officials.

Mullah Dadullah, the main Taliban military commander, claimed responsibility. The attack was targeted at "U.S. spies," he said, speaking by satellite phone from an undisclosed location.

The attack took place before shops opened. Security forces sealed off the area as they sifted the wreckage from the blast.

Blood splattered the road and a bicycle caught in the explosion lay twisted by the side. The bomber's body was ripped apart.

Violence has risen in Afghanistan with the end of winter as the Taliban step up suicide attacks as part of a return to conventional guerrilla tactics this year.

On Tuesday, a suicide bomber disguised as an Afghan soldier blew himself up in front of a police headquarters and killed at least four policemen in the southern province of Helmand.

Last year saw the worst fighting since late 2001 when U.S.-led coalition forces ousted the Islamist Taliban, and 2007 is expected to be a crunch year for both sides.

Separately, authorities in the southern province of Kandahar said they were hunting for the kidnappers of four Health Ministry officials, including a woman, who were abducted on Tuesday by unidentified armed men.

The officials were working on a project funded by the United Nations High Commissioner for Refugees. There were no claims of responsibility but the Taliban have kidnapped foreigners and Afghans in the past.

PHOTO CAPTION

A policeman gestures at a suicide bomb blast site in Kabul March 28, 2007. (Reuters)