Afghan police officers at the scene of a suicide bomb attack at the Interior Ministry headquarters in Kabul on Wednesday. CreditMassoud Hossaini/Associated Press  

KABUL, Afghanistan — A suicide bomber killed six policemen after detonating his explosive vest at the entrance gates of the Interior Ministry headquarters on Wednesday, ministry officials said, penetrating nearly to the heart of the Afghan security establishment.

Wearing a military uniform, the attacker got through two security checkpoints. At the third one, in front of the gates, he set off an explosive amid a group of policemen heading into work at the ministry, which is in charge of Afghanistan’s police forces. The headquarters is on a heavily guarded street that is also home to several Western embassies.

The Taliban claimed responsibility for the attack, and said hundreds of Afghan policemen had been killed or wounded.

The bombing came after a series of Taliban attacks in the capital on foreign targets, as well as two on election facilities, amid heavy security in preparation for Saturday’s presidential election.

The authorities have closed at least two guesthouses and 11 restaurants frequented by foreigners in an apparent attempt to prevent further attacks on expatriates working here, according to owners of the establishments.

However, the spokesman for President Hamid Karzai, Aimal Faizi, on Wednesday strenuously denied that authorities had closed any restaurants out of fear for foreigners’ safety.

The only closing, Mr. Faizi said, was of the Gandmack Lodge, a guesthouse and restaurant, which was ordered shut Tuesday by intelligence agents of the National Directorate of Security. The manager of the lodge said he had been told it was shut for security reasons until after the elections.

Mr. Faizi said the president’s national security council had decided to order the Gandamack closed because of intelligence it received about the guesthouse. “It was a nest for intelligence agencies meeting there,” he said.

The Gandamack has been popular with journalists and aid workers since its opening shortly after the fall of the Taliban. At its initial location, it was the former home of one of Osama bin Laden’s wives.

Peter Jouvenal, a former television cameraman who is the owner and founder, said the only guests in residence when the closing order came were six journalists, including Americans, Britons and Germans.

“Because we were quite popular we were perceived as a potential target,” Mr. Jouvenal said. “If anything happened it would reflect very badly on the Afghan government.”

Mr. Faizi said no other establishments were ordered closed, although authorities did offer security advice to many of them.

However, 11 restaurants popular with foreigners were contacted on Tuesday, and all related having been visited by the police or security directorate agents and ordered to close until after the elections. Some were allowed to continue serving takeout meals, but only if foreigners were not on their premises.

On Wednesday, an employee of the Euro Guesthouse said the directorate had also prohibited it from taking in foreign guests until after the election.

“We asked these places of business to be closed for a short while because we have information and we do not think they have security precautions that they need,” said a senior Afghan security official, speaking on the condition of anonymity because he was discussing internal government conversations. “We know why we asked them. They are not ‘spy dens,’ ”

A young man passing by the scene of the bombing Wednesday was contemptuous. “If they can’t secure and protect their own ministry,” he said, “how can they claim to be able to secure the election and protect the voters on Saturday?”