Graham Norton may be forced to leave Channel 4 if his new US chat show is successful, the Media Guardian reports today.

The Irish comic is currently contracted with the network through to March 2004, after which his new contract with US station Comedy Central will begin.

Technically Norton could continue with Channel 4 in the UK, although demands on the other side of the Atlantic could make his nightly C4 chat show implausible.

"I think Graham remains an incredibly important part of the mix on Channel 4. But he has got ambitions for America," Channel 4 CEO Mark Thompson told the website.

"I'd love to see Graham continuing to appear on the channel. We will be talking to him and his production company, So Television, about the future but I very much hope we can encourage him to remain with Channel 4."

Returning director of programmes Kevin Lygo is expected to pursue the renewal of Norton's contract as a first priority.