At least 30 people are reported to have been killed by a car bomb during morning rush hour in Somalia's capital.

The blast took place at a checkpoint at a busy intersection in Mogadishu.

"The blast was devastating, and I could confirm more than 20 civilians killed, there were many more wounded," police officer Ibrahim Mohamed was quoted by news agency AFP as saying.

No group has yet claimed responsibility for the bomb but al-Shabab militants have often carried out attacks there.

Al-Shabab - a group of Islamist militants, allied to Al-Qaeda - has waged an insurgency for more than 10 years. It was forced out of the capital in 2011 but still controls areas of the country.