The United States has confirmed that Ahmed Abdi Godane, a founder of Somalia's al-Shabab group, was killed in a US air strike this week.

"We have confirmed that Ahmed Godane, the co-founder of al-Shabab, has been killed," the Pentagon press secretary Rear Admiral John Kirby said in a statement on Friday.

 Ahmed Abdi Godane

On Tuesday at least six people were killed as the US hit a convoy of senior al-Shabab leaders. Since then the US was assessing the results to see who died.

The attack targeted vehicles and encampment near Barawe, the armed group's base of operations.

The US said the targets were senior commanders of al-Shabab, including Godane, also known as Abu Zubeyr.

Confirming Godane's death on Friday, the US statement called it a "major symbolic and operational loss" for the al- Qaeda-affiliated organisation.

The US State Department has listed Godane as one of the world's eight top "terror" fugitives and analysts say his death would mark a serious setback for al-Shabab.

Al Jazeera's Mohammed Adow, reporting from neighbouring Kenya, said that it was during Godane's leadership that al-Shabab established a foothold in most parts of Somalia and led the group to cross its borders and carry out attacks in countries like Kenya and Uganda. 

Somalian President Hassan Sheikh Mahmoud, who said the airstrikes against al-Shabab's leadership were carried out with his government's knowledge,  called on "the group's fighters to embrace peace and take advantage of a 45-day amnesty period declared by his government".

Last October, US special operations forces launched an attack on a house in Barawe against another top al-Shabab commander but were forced to withdraw without killing their target.

Al-Shabab fighters are fighting to overthrow the Somali government, regularly launching attacks against state targets and in neighbouring countries that contribute to the African Union force.

Following the Pentagon announcement, Somali President Hassan Sheikh Mohamud reiterated his government's amnesty offer to al-Shabab fighters saying they should reject being "pawns of an international terror campaign".

Al Jazeera's Mohammed Adow reports from Somalia on the offensive against al-Shabab

"I say to the members of al-Shabab: Godane is dead and now is the chance for members of al-Shabab to embrace peace," Mohamud said in a statement

"While an extreme hardcore may fight over the leadership of al-Shabab, this is a chance for the majority of members of al-Shabab to change course and reject Godane’s decision to make them the pawns of an international terror campaign," he said.

Earlier this week the Somali government gave fighters 45 days to accept the amnesty offer following the US air strike on Godane.

"Those who choose to remain know their fate. Al-Shabab is collapsing," Mohamud warned.

Source: Al Jazeera and agencies