The award is the most prestigious prize in UK literature and the proposed changes have prompted fears that "a great British institution" could be destroyed.

Lisa Jardine is head of the 2002 judging panel

As well as UK authors, Commonwealth and Irish writers can also enter The Booker Prize.

Martyn Goff, chairman of the Man Booker Prize Advisory Committee, said a working party was being set-up to look into possible extensions for the prize, including "the feasibility of expansion of the prize into America".

He added: "The committee has discussed the idea of expansion into America in the past, and, now that resources are available, it could become possible.

"No decision has yet been made."

The rules will remain the same except for the admission in some way or other of American authors

Martyn Goff Booker Prize

The financial services firm Man Group recently pledged �2.5m to the prize over five years.

The award will be renamed The Man Booker Prize and the winner's cheque will be �50,000, up from the current sum of �20,000.

But the organisers of the prize have denied that the new sponsor prompted the discussion because it wanted to raise its profile in the US.

The proposal has already prompted criticism from the chair of this year's Booker panel, Lisa Jardine, who says the award would become "blandly generic as opposed to specifically British".

Professor Jardine, a writer, critic and broadcaster, told BBC Radio 4's Today programme that the organisers should have "taken a little less money and retained a little more flexibility".

"The Booker will become as British an institution as English muffins in American supermarkets," she said.

"It will become more blandly generic as opposed to specifically British. This will completely change the character of the prize."

But Mr Goff said the award would remain the same but bigger.

"The rules will remain the same except for the admission in some way or other of American authors," he has said.

"But it will be a question of adding it to the prize as it is."

'Drowned out'

Its last five winners have been Australian, Canadian, South African, English and Indian.

But Prof Jardine said those voices could be "drowned out" by US novelists who produce grander works.

This year's Booker long list - about 25 titles under serious consideration for the prize - will be announced in mid-August, and the shortlist in mid-September.

The judges will announce the winner at an awards dinner in late October.