The Iranian judiciary chief, Ayatollah Mohammed Yazdi, has called for a speedy investigation into the killings of a veteran opposition leader and his wife.

Mr Yazdi expressed regret over the deaths of Dariush Foruhar and his wife, Parvaneh, who were stabbed to death at their home in Teheran on Sunday.

Close associates said the killing was politically motivated.

Mr Foruhar was an opponent of the former Shah.

He also served as a minister in the first government after the Islamic revolution but had criticised the current Islamic government for violating political and human rights.