Mogadishu - Somali al-Shabaab militants fought a gunbattle with African Union troops after ramming a car laden with explosives into their base south of the capital Mogadishu early on Friday, military officials and a spokesperson for the group said.The dawn attack in Leego - along the main road connecting Mogadishu and the city of Baidoa - came as residents gathered for morning prayers."A car bomb rammed into the AU base in Leego and this was followed by heavy exchange of gunfire," Major Nur Olow, a military officer, told Reuters. "First, AU forces opened fire at the speeding car bomb. The car forced its way in."Sheikh Abdiasis Abu Musab, a spokesperson for the al-Qaeda-aligned group, said the militants had rammed the car bomb into the base and that "heavy fighting goes on inside the base."Several attacks by militantsAn African Union spokesperson could not be reached for comment.There were no immediate details of casualties.This was the latest of several attacks by the Islamist militants, fighting to overthrow the Western-backed Mogadishu government, since the Muslim fasting month of Ramadan began a week ago.Additional security had been deployed for Ramadan, as officials had warned of a heightened security risk as al-Shabaab's fighters have often launched attacks during this period.Last week, al Shabaab attacked an African Union convoy with Ethiopian soldiers along the same route.It was also behind two attacks in Mogadishu in the last week. On Sunday, militants stormed a national intelligence agency training site and, on Wednesday, it targeted military instructors from the United Arab Emirates.