At least three people are feared to have been killed and several others wounded in a suicide bomb attack on Wednesday, which targeted a United Nations (UN) convoy outside the Aden Adde International Airport in Somalia's capital, Mogadishu, security officials said.

"The bomber drove in between the security escort and the UN armored vehicles and detonated the car, ramming into one of the escort vehicles," police officer Mohamed Liban told the AFP news agency. African Union troops and Somali security forces closed all roads leading to the airport.

The peacekeeper convoy was reportedly ferrying staff between Mogadishu's heavily-fortified airport and a protected UN base in the city at the time of the attack.

Chain of attacks

Responsibility for the attack was not immediately claimed, but the al Qaeda-affiliated terrorist group al Shabab has frequently carried out suicide and gunfire attacks in Mogadishu.

In a similar attack in February, six people, including Somali guards, passers-by and shop owners, were killed when a suicide bomber targeted a convoy carrying UN staff near the airport.

Over the last two weeks, al Shabab has also claimed responsibility for two attacks against Kenyan civilians near the Kenya-Somali border, including the massacre of 36 non-Muslim quarry workers on Tuesday.

ksb/jr (AFP, AP, dpa)