Two extensive police searches have failed to trace exchange student Jonny Dorey, who left his Virginia campus with his mountain bike and backpack on 2 March

Fears are growing over a British exchange student who disappeared 12 days ago from a university in Virginia. Jonny Dorey, 22, a geography student from Guernsey, was last seen leaving the Virginia Commonwealth University campus in Richmond, US, on 2 March with his mountain bike and a backpack.

He last used his mobile phone that morning, from Belle Isle, a rural area close to the campus popular with mountain bikers and walkers. Despite two extensive searches in the area, police are no further forward in tracing him or his bike.

A family friend, Bob Beebe, said yesterday that his parents, Alan and Debbie, were "very distressed" but remained focused on trying to find him.

Beebe said that Dorey's disappearance was "uncharacteristic" and that, two days before he went missing, he had been making travel plans with a friend by email.

"This week is spring break over there and he and this friend had been making plans. He was very happy, he's a very lovable lad."

Beebe said that Dorey's parents, who have travelled to the US to help in the search, have now taken on an experienced local mountain bike guide who knows every track in the area, in the event that he may have wandered further afield.

Police are trying to piece together Dorey's last movements. They have said there is no evidence of foul play.

They have been looking at his computer and phone records in a bid to piece together his last movements.

Beebe said it was hoped that these clues, along with help from people in the local area, would help the search team to retrace Dorey's steps and follow his planned movements.

"Someone somewhere must have seen Jonny Dorey that Tuesday," he said.

"All it takes is somebody sending a message from an internet cafe, a phone box, Twitter, and that single piece of information will help to complete that very complex jigsaw."

VCU has put out a $5,000 reward for information, and his friends have set up a Facebook group to share any information, which now has almost 20,000 members.