Booker fiction prize loses main sponsor

Britain's leading literary award, the Man Booker Prize, faces uncertainty after its main financial backer announced it is ending its sponsorship after almost two decades.

Investment manager Man Group says it will stop funding the Man Booker and Man Booker International prizes after 2019.

The firm says it has donated STG25 million ($A46 million) to the Booker Prize Foundation since 2002.

The prize foundation says its trustees "are in discussion with a new sponsor and are confident that the new funding will be in place for 2020".

Founded in 1969, the prize was originally open to English-language writers from Britain, Ireland and the Commonwealth. US authors became eligible in 2014, a move that remains contentious.

The international prize, founded in 2005, goes to works in translation.