The family of a Pakistani woman jailed in the US has pleaded with the jihadist group Islamic State in Iraq and Syria (IS) to release the British aid worker Alan Henning and other hostages.

Dr Fawzia Siddiqui, whose sister's release has been demanded by IS as part of a prisoner swap, said her sister would be ''distraught and devastated'' to discover that militants were using her name to justify their actions.

Dr Aafia Siddiqui is serving an 86-year jail term for the attempted murder of an FBI agent in disputed circumstances. The family has said she was innocent and has been wrongly held in US custody since 2003.

Speaking to the BBC's Shahzeb Jillani in Karachi, Dr Fawzia Siddiqui appealed for the kidnappers to ''show mercy'' and release the hostages.