Channel 4 is to investigate a claim that it misled viewers in a survival series, in the latest allegation of reality being manipulated on a TV show.
Channel 4 calls Grylls "a cross between Ray Mears and Rambo"
Born Survivor featured British adventurer Bear Grylls dealing with "perilous situations" in the wild.
But a crew member told the Sunday Times some nights were spent in hotels.
Channel 4 insisted Grylls was never billed as working entirely unaided, but promised to raise the matter with the production company that made the show.
American survival consultant Mark Weinert, who was recruited by Diverse Productions, told the paper Grylls claimed to be stranded on a desert island on one occasion.
However, he was actually in Hawaii and spent some of his time there in a motel, Mr Weinert alleged.
Another time, he added, Grylls was filmed building a raft by himself, whereas the crew had actually put it together and dismantled it beforehand, to ensure that it worked.
And in a further episode, supposedly "wild" horses rounded up by Grylls had come from a local trekking facility, he claimed.
Channel 4 said in a statement that Born Survivor was "not an observational documentary series, but a 'how-to' guide to basic survival techniques in extreme environments".
"The programme explicitly does not claim that presenter Bear Grylls' experience is one of unaided solo survival.
"For example, he often directly addresses the production team, including the cameraman, making it clear he is receiving an element of back-up."
The broadcaster said Grylls carried out his own stunts and did place himself in perilous situations, "though he does so within clearly-observed health and safety guidelines required on productions of this kind".
"However, we take any allegations of misleading our audiences seriously and will be looking into this further with Diverse over the next few days."
The series was originally made for the Discovery Channel in the US and was acquired for UK transmission by Channel 4.
Diverse Productions declined to elaborate on Channel 4's statement, while Grylls's agent was unavailable for comment.