London, Sep 13 (IANS): The family of a British man being held hostage by Islamic State (IS) militants have appealed to his captors to make contact with them, media reported Saturday.

A statement from the family of David Haines said the militants, who have beheaded two US journalists, James Foley and Steven Sotloff, had not replied to their previous messages, BBC reported.

Haines, 44, was taken hostage in the village of Atmeh, in the Idlib province of Syria, in March 2013.

He had been helping French agency Acted deliver humanitarian aid, having previously helped local people in Libya and South Sudan.

IS has threatened to next kill Haines unless US air strikes on its positions in Iraq are halted.

The threat was made during a video posted online showing the killing of US journalist Steven Sotloff earlier this month.

"We are the family of David Haines. We have sent messages to you to which we have not received a reply. We are asking those holding David to make contact with us," the statement made by Haines' family said.

Foreign Secretary Philip Hammond has said that the government was doing "everything" it could to protect Haines.

The militant group previously known as the Islamic State of Iraq and Greater Syria (ISIS) have seized large swathes of territory in Iraq and Syria since June, declaring a new caliphate.