A US man sentenced to 35 years in jail for his role in the 2008 Mumbai attacks has been pardoned by an Indian court after he agreed to be a witness.

David Headley appeared before a court in Mumbai via video conference and agreed to give full details of the planning and execution of the attacks.

Headley, 52, pleaded guilty and co-operated with the US to avoid the death penalty and extradition to India. More than 160 people were killed by gunmen in the November 2008 attack. The Mumbai court told Headley that his pardon was conditional and it expected him to fully disclose all the information he had on the attacks. He appeared before the court through a video link from an undisclosed location in the US.

"He has become a government witness. The court decided to pardon him because his testimonywill give more details of the attacks. He will testify on 8 February," Indian prosecutor Ujjwal Nikam told journalists in Mumbai.

Headley was sentenced in the US in 2013 on 12 counts, including conspiracy to aid militants from the Pakistani group Lashkar-e-Taiba (LeT) which India blames for carrying out the attacks.

Headley's US lawyer John Theis told BBC Hindi that he did not "expect anything substantially different from what he (Headley) has already said and it will be consistent with his testimony in Chicago”. "It [Headley's pardon in India] also doesn't affect the 35 year jail term that he's serving in the US," Theis added.

Headley was sentenced in the US in 2013 on 12 counts, including conspiracy to aid militants from the Pakistani group Lashkar-e-Taiba (LeT) which India blames for carrying out the attacks.