Police in Belgium were today investigating a claimed sighting of Sussex man Ian Gilbert, who vanished during a stag night in Ostend.

It is understood that a member of the public contacted police in the port town to say they had seen a man fitting Mr Gilbert's description in a bar.

Best man Mr Gilbert, 25, of Crowborough, disappeared early on Saturday while walking back to his hotel with 25 friends, including groom Mark Rosier, 27.

A massive search was entering its sixth day today amid fears that Mr Gilbert, an advertising rep known as Golly, could have fallen into the sea.

Divers were called in yesterday to search for him and the Belgian air force has been searching the coastline.

Today close family friend Paul Gray said: "The police are investigating a sighting but it is yet to be confirmed.

"It is the first positive piece of news, and that is a good thing, but I find it highly unlikely that Ian is sitting around in bars. We will have to wait and see what comes of it."

A Sussex Police spokeswoman said there had been an unconfirmed sighting of Mr Gilbert.

A tearful appeal by Mr Gilbert's wife Charlotte, 34, was aired on Belgian TV yesterday.

Choking back tears, she said: "If you are out there, Golly, come home. Please come home."

Friends say Mr Gilbert's bank cards have not been used since his disappearance and his passport was left in the group's hotel, prompting fears he may have fallen into the sea.

There was also concern he might have been mugged as he was in charge of the group's kitty of several hundred pounds.

A reward put up by friends of Mr Gilbert for information has been upped from £5,000 to £15,000.