MOGADISHU: A suicide bomber killed 18 people including three Somali government ministers at a ceremony in a Mogadishu hotel on Thursday, officials said.

The blast is the most serious attack on the transitional federal government (TFG) since the launch of an Al-Qaeda inspired Islamist insurgency that has brought new strife to the Horn of Africa nation.

Several ministers from the UN-backed government were at a graduation ceremony for students at the Shamo hotel when the explosion went off.

A security official said 18 people were killed and that the blast was caused by a suicide bomber. "Most of the vicitms were students," the official said.

A hotel security official said the suicide bomber was probably hidden among the guests.

Higher Education Minister Ibrahim Hassan Addow and Health Minister Qamar Aden were killed on the spot and Education Minister Mohamed Abdullahi Waayel died shortly after the blast, a senior government official said.

Sports Minister Suleyman Olad Roble was among the injured, the official added.

Two journalists, one from Shabele Radio and another from Al Arabiya television, and a doctor were also killed, a source at the hotel said.

AFP photographer Mohamed Dahir sustained slight injuries.

"We were waiting outside the conference room when there was a huge explosion. I found myself on the ground in the middle of the smoke and screaming," said Dahir.

"I went to get my camera, and that's when I saw the bodies of the three ministers."

New EU foreign policy chief Catherine Ashton condemned the "cowardly attack" and promised to seek a coordinated international response to Somalia's woes.

"I condemn in the strongest terms possible this cowardly attack against civilians including students, doctors and journalists," Ashton said in a statement.

In Kampala, the acting head of AMISOM, the African Union peacekeeping force in Somalia, Wafula Wamunyini, said the attack "was intended to intimidate and blackmail the TFG. We condemn this incident in the strongest terms."

Thousands have been killed in Mogadishu in recent years as Islamists battle for control of the capital.

The Somali insurgents launched a fresh offensive against the transitional government of President Sharif Sheikh Ahmed on May 7 and clashes since then have left more than 250 dead while an estimated 120,000 people have fled the city.

The Shebab militia have vowed to bring down the government and force all African Union peacekeepers out of the country.

Somalia has had no effective government since President Mohamed Siad Barre was forced out of power in the early 1990s.

The Islamists control large swathes of Mogadishu as well as much of the centre and south of the country.

The transitional government only exists with the backing of the 5,000 AU peacekeepers from Burundi and Uganda.

At least 60 peacekeepers have been killed since they were deployed in March 2007 to protecting strategic sites in the seaside city such as the presidency, the port and the airport. A twin suicide bombing atMogadishu airport in September killed 17 peacekeepers.

Wamunyini ruled out any withdrawal of peacekeepers following the new attack however: "We want to ensure everyone we are going to continue with our mission. We are going to continue providing our services."

The attack came a day after Wamunyini expressed frustration at the failure of African countries to honour troop commitments. The force is meant to have 8,000 soldiers.

Wamunyinyi said the threat posed by Islamist insurgents had been exaggerated, scaring off countries from deployments.

"We feel really frustrated and let down that several African nations have not honoured their commitment to send troops, but the media have made it difficult for them to deploy," he said.

"And nobody seems to appreciate the AMISOM has accomplished a lot," he said at the press conference in Kampala where military chiefs and other AU officials are meeting on ways to boost the force.