A top United Nations relief official visited Somalia on Saturday for the first time in 10 years and called on the Somalia authorities to let humanitarian aid to reach vulnerable people in the war-ravaged nation.

However, the UN's emergency relief co-coordinator John Holmes' visit to Mogadishu was marred by explosion which killed four people and several wounded when an explosive hit a vehicle south of the Somali capital Mogadishu.

Paddy Ankunda, the spokesman of the African Union peacekeepers in Somalia confirmed by telephone from Mogadishu that a car bomb killed four people in the south of the city as Holmes' convoy left the airport.

"I can confirm that four people were killed in the incident and we do not know how many are injured. Investigations have been launched to establish the cause of the explosion," said Ankunda.

Senior intelligence official Ibrahim Mohamed Ahmed is reportedly one of those killed in the blast. It is believed that the explosion was unrelated to Holmes' visit.

Holmes, who is on a two-day visit to Mogadishu which recently suffered the worst violence in 16 years, said he would press on Somali leaders to protect civilians who have borne the heaviest brunt of years of fighting.

"There is a serious humanitarian crisis and I want to come and see for myself to talk to the authorities to try to pressure them on the need to do all they can to facilitate humanitarian aid," Holmes said. "It is their responsibility to look after civilians to protect civilians and at the very least to not obstruct aid."

The UN relief official's visit comes two weeks after Somalia's government declared victory over a bloody Islamic insurgency which left more than 1000 people dead and displaced 400,000 others.

Holmes said the government had to look after its civilians, who have borne the brunt of years of fighting.

But he said the African Union could not boost its peacekeeping forces in the capital until the Ethiopian-backed transitional government improved security.

Holmes visited a cholera treatment center next to the UN compound before meeting Somali President Abdullahi Yusuf Ahmed.

The capital has been mostly calm since the government declared victory over the insurgents and many residents are starting to return to their homes.

Holmes is the first highest ranking UN official to visit Mogadishu in more than a decade.

Source: Xinhua