Media playback is unsupported on your device Media caption Caroline Wyatt reports: ''Security here was seen as tight''

A senior IMF official and four UN employees were among 21 people killed in a suicide bomb and gun attack on a restaurant in Kabul, officials say.

Wabel Abdallah, the head of the IMF's Afghanistan office, and the UN civilian staff died in what UN chief Ban Ki-moon said was a "horrific attack".

The 13 foreign victims included Canadians, UK, US, Lebanese, Russian and Danish citizens.

The Taliban said they carried out the attack late on Friday.

Five women were among the dead at the city's popular Taverna du Liban, and at least five were injured, police say.

'Devastated'

The restaurant in Kabul's Wazir Akbar Khan area is popular with foreign nationals, diplomats and aid workers, and was busy with diners at the time of the attack.

Kamal Hamade, owner of the Taverna du Liban, made the best chocolate cake, the best Lebanese food and, he thought, the best evacuation plan. The plan wasn't good enough to save him and other foreigners and Afghans who died with him when the Taliban came. But it did save many lives. I know from my own visits when in Kabul that Kamal did everything possible to make his restaurant a home away from home. Whatever food you ordered, he brought double the amount. He proudly introduced us to Afghan chefs he trained to make Lebanese specialties and Afghan guards who kept his place safe. We talked about his native Lebanon, his risky time in Baghdad, but most of all, his commitment to his new home. Now his doors are destroyed and, with them, a little of the hope that Kabul can ever be the safe inviting place he wanted the Taverna to be. Britons die in blast

A suicide attacker detonated his explosives outside the gate of the heavily fortified restaurant, Deputy Interior Minister Mohammad Ayoub Salangi said.

He said two gunmen then entered the restaurant and started "indiscriminately killing" people inside.

International Monetary Fund chief Christine Lagarde later confirmed that Wabel Abdallah, 60, a Lebanese national, was among those who died.

"This is tragic news, and we at the fund are all devastated," Ms Lagarde said in a statement.

Meanwhile, UN Secretary General Ban Ki-moon condemned "in the strongest terms the horrific attack", his spokesman said.

"Such targeted attacks against civilians are completely unacceptable and are in flagrant breach of international humanitarian law. They must stop immediately," Mr Ban was quoted as saying.

The UK Foreign Office confirmed that two British nationals were among those killed in the incident.

At least two US citizens died in the attack, the US embassy in Kabul said.

Kamal Hamade, the well-known Lebanese owner of the restaurant, and five women were among the dead. A number of people were injured.

Image copyright AP Image caption Security forces flooded the area soon after the attack.

Image copyright AFP Image caption The restaurant, in the heart of Kabul's embassy district, was popular with diplomats and foreign workers.

Image copyright Reuters Image caption The explosion wrecked the restaurant and destroyed nearby vehicles.

"I was sitting with my friends in the kitchen when an explosion happened and smoke filled the kitchen," Abdul Majid, a chef at the restaurant, told AFP news agency.

"A man came inside shouting and he started shooting. One of my colleagues was shot and fell down. I ran to the roof and threw myself to the neighbouring property."

The attackers were eventually shot dead by the security forces when they arrived at the scene.

Media playback is unsupported on your device Media caption Ari Gaitanis UN Spokesman: "It is a very heavy day here for us at the UN in Afghanistan"

The BBC's Mahfouz Zubaide heard the blast and gunfire from at least two kilometres away. He said the gunfire went on sporadically for about 10 minutes.

The Taliban said it carried out the attack, saying it had been deliberately targeting foreign officials.

Security continues to be a major concern in Afghanistan. The last remaining contingent of Nato-led forces is due to leave by the end of the year, having handed over security to Afghan forces.

Washington is pushing Afghan President Hamid Karzai to sign an agreement which would allow some US troops to stay behind after this year's withdrawal.

The Taliban told the BBC's John Simpson earlier this week that it was now back in control of large areas of Afghanistan and was confident of returning to power after Western troops left.

Our correspondent says it is hard to believe the Taliban could make a comeback as things stand, but their takeover of Kabul in 1996 was unexpected, and they could be strengthened if a weak, corrupt president is elected in April.