Somalia's government has offered an amnesty to fighters with al-Shabab, the armed group whose leader was reportedly targeted on Monday night in a US air strike.

Following a cabinet-level security meeting, Somali authorities gave al-Shabab fighters 45 days to take up the offer, Security Minister Khalif Ahmed Ereg told reporters on Wednesday in the Somali capital of Mogadishu.

He said the government "will create a better livelihood to build their future for those who meet the deadline".