KABUL  - A female bomber killed 12 people, including South Africans, in Kabul on Tuesday in the deadliest single attack claimed to avenge a US film that has sparked a week of deadly protests across the Muslim world.

The bombing brings to more than 30 the number of people now killed in a violent backlash over a YouTube trailer for the film, “Innocence of Muslims”, believed to have been produced by a small group of extremist Christians. Security officials said nine foreigners were among those killed on a major highway leading to Kabul airport when the bomber blew her station wagon up alongside a minivan carrying foreign workers.

The South African foreign ministry confirmed that eight of its citizens, all believed to have been men working for a private aviation company, were killed. An AFP photographer saw at least six bodies lying among the wreckage of a gutted minivan, and another vehicle destroyed by flames still burning in the middle of the highway, with debris flung all around.

Hezb-i-Islami, the second largest insurgent group after the Taliban who have been fighting US-led troops and the government for 10 years, claimed the attack.

“The bombing was in retaliation for the insult to our Prophet (PBUH),” spokesman Zubair Sidiqi told AFP in a telephone call from an undisclosed location. It is extremely rare for the faction to claim a suicide attack in Afghanistan. It is also rare for women to carry out suicide attacks.

Taliban fighters last week stormed a British-run airfield, killing two US Marines and destroying six US fighter jets also to avenge the film.

A week of furious protests outside US embassies and other American symbols in at least 20 countries have killed 19 other people, including the American ambassador to Libya and three other US diplomats in the North African country.

In Lebanon, the head of Shia Muslim movement Hezbollah, which is blacklisted in the United States as a terrorist organisation, made a rare public appearance to warn of “very dangerous” repercussions if the entire film is released.

Tens of thousands of demonstrators poured into the streets of southern Beirut to denounce the film at the request of Nasrallah, who has called for a week of protests over the film, describing it as the “worst attack ever on Islam”.

“The US must understand that releasing the entire film will have dangerous, very dangerous, repercussions around the world,” he told the rally.

The filmmaker Nakoula Basseley Nakoula, a 55-year-old Egyptian Copt and fraudster who was sentenced to 21 months in prison in the US in June 2010, has not been seen since Saturday when he was questioned.

On Tuesday, fresh protests erupted in Afghanistan and Indonesia. Several hundred university students threw stones at police and set fire to pictures of US President Barack Obama in the northern Afghan city of Kunduz.