Shebab militants launched a major suicide raid on Sunday against a military intelligence base in the capital Mogadishu, setting off a car bomb before storming inside, security officials said.

Shebab militants launched a major suicide raid on Sunday against a military intelligence base in the capital Mogadishu, setting off a car bomb before storming inside, security officials said.

"There is an attack against a base belonging to the security forces. The violent elements used a car bomb to get inside the compound. There was a heavy exchange of gunfire," said Adan Mohamed, a Somali security official.

Witnesses near the base, belonging to the internationally-backed government's National Intelligence and Security Agency (NISA), reported a loud explosion followed by intense gunfire.

"There was a heavy explosion and in seconds heavy gunfire broke out. We cannot go outside the house because of the shooting," said Abdulahi Yare, a resident who lives near the base.

In a brief statement, NISA said the attack had failed.

"The attack was successfully thwarted by our forces. None of our buildings nor bases were entered," it said.