The United States is offering millions of dollars in rewards for information leading to the capture of leaders of the Somali militant group al-Shabab.

It is the first time the US has offered money for specific members of the group, which announced its allegiance to al-Qaeda earlier this year.

“The group is responsible for the killing of thousands of Somali civilians, Somali peace activists, international aid workers, journalists and African Union peacekeepers,” the State Department said.

It has put a price of $7m on al-Shabab’s founder and commander, Ahmed Abdi aw-Mohamud Godane.

Al-Shabab still controls much of the country but is under pressure from Ethiopian troops, pro-government militias and the African Union force, which has US and European funding.

Shabaab leaders dismissed the US bounties – collectively reaching $33m – for tip-offs for the arrest of top leaders, vowing to continue their extremist fight.

“The non-believers know who are the good Muslim leaders – and that is why the money is offered for their whereabouts,” said website Somalimidnimo.com, which is close to Shabaab leaders, adding that the offer would not work.

“While some mujahedeen leaders have already been killed by such plans, others continue the jihad,” the site added.

The US bounties came as African Union forces make key advances against the group.

African Union and Somali government forces last week captured the town of Afmadow, a strategic militant base in the south of the country.