Somalia's Al-Shabaab use woman suicide bomber in UN attack

Wednesday's bombing in the Somali capital that killed seven people was a rare instance of al-Shabaab using a female suicide bomber, the extremist group and Somali officials have said.

While initial reports indicated that a male suicide bomber had targeted the Mogadishu mayor's office, the Associated Press reported on Thursday that the attacker had been confirmed as a woman.

Earlier suspicions that the attacker had been planning to target the new UN envoy to Somalia were also confirmed by al-Shabaab's military spokesman Abdiaziz Abu Musab.

The unnamed female bomber walked into a security meeting and blew herself up close to the mayor, a senior police officer said. 

The attack is only the fourth time al-Shabaab has used a female bomber in a suicide attack.

The death toll for the bombing rose to seven on Thursday, with the seriously wounded Mayor Abdirahman Omar Osman left in a coma.

He and other officials were expected to be airlifted to Qatar for treatment, said Mohamed Ahmed, a government official at the hospital treated the mayor.

The new UN envoy James Swan had visited the mayor's office for a brief visit on Wednesday and left the compound less than an hour before the bombing, an official at the office said.

Swan condemned the "heinous attack" in a statement, saying it "not only demonstrates a violent disregard for the sanctity of human life, but also targets Somalis working to improve the lives of their fellow Somalis".

It is yet unclear how the attacker manager to enter the mayor's office as visitors are required to pass through at least four metal detectors.

Some security officials suspect the bomber coordinated with corrupt officials, offering them bribes for access to the compound.

Somali government officials and buildings such as the presidential palace are routinely targeted with bombings by al-Shabaab.

But Wednesday's attack seemed to be a shift in tactics, as the militant group has rarely managed to infiltrate heavily fortified government buildings in the past without first detonated one or more car bombs.

The al-Qaeda-linked group, which opposes Somalia's federal government and wants to impose an extreme interpretation of Sharia law. It is considered by many to be the deadliest militant group in Africa.

It has carried out attacks in East Africa beyond its base in Somalia, including in neighbouring Kenya, despite having been ousted from its bases in Mogadishu in 2011.

The Somalia-based organisation was chased out of Mogadishu years ago but still controls parts of the Horn of Africa nation's south and central regions and is a frequent target of US airstrikes.