At least three government police officers were killed and four others wounded on Thursday after a suspected Islamist suicide car bomb exploded outside the gate of the international airport in Somalia's capital Mogadishu, officials and witnesses said.

"Three of our officers died when the police at the gate of the airport fired on car laden with bombs. Four of the police officers were also wounded. We are still engaging some elements hiding around," a Somali government security officer at the airport who asked for anonymity told Xinhua.

The government officer also said that civilians could also have been affected by the "huge" blast that rocked the area where many travelers and relatives were waiting.

Witnesses at the scene of the blast said that a Sport Utility Vehicle (SUV) laden with explosives was used in the attack while some reports suggest it was twin car bomb attacks.

"We heard two separate loud explosions from the airport and after I looked at the window I could see huge smoke coming from the outside gate of the airport," Mohamed Muse, a resident near the airport told Xinhua by phone.

The attackers were reported to have worn Somali government police uniform and were riding an SUV and a pickup car which opened fire before ramped into the blocks of concrete protecting the front gate of the airport which is used as base for the African Union (AU) peacekeeping forces.

No group has so far claimed responsibility for the attack but a pro-Islamist radio station in Mogadishu said that the attacks were carried out by "Al Shabaab Mujahideen," but the group has not officially commented on the attack.

Neither the Somali government nor the AU peacekeeping officials have spoke on the assault on the airport which comes as renewed fighting has been escalating in Mogadishu after Islamist Al Shabaab movement announced a major offensive against the government and AU troops two weeks ago.

The group has earlier carried out a deadly attack on a hotel in the Somali capital frequented by government officials. At least 33 were killed including four government MPs.

Islamist group of Al Shabaab announced late last month they plan to wage an all out offensive to "finish off" the Somali government forces and AU peacekeeping troops based in Mogadishu.

The radical group, considered a terrorist entity by a number of world governments including the United States, controls much of south and center of Somalia and wants to establish an Islamic state in the war torn east African country.