Police investigating the reported death of a British man in Syria said they are carrying out a search of a house in Manchester today.
"As part of this inquiry, officers are also providing support to the family and are speaking to them to understand how a man from the North West came to be reportedly killed in Syria," Detective Chief Inspector Will Chatterton of the north west counter-terrorism unit said.
"As part of the National Prevent Strategy, officers are working to assess how people are drawn into travelling to Syria to become involved in conflict and how to prevent others doing the same.
"We know that some have already lost their lives or been detained by the regime and badly treated.
"It is vital that anyone who has concerns that someone may be considering such travel informs the authorities," said Inspector Chatterton.
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Some 66 people have been killed after the plane they were travelling on crashed in southern Iran.
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Police say that anyone who sees Whitehouse should not approach him, but instead call them on 999 and quote incident 23 of 18 February.