By Paul Majendie

LONDON (Reuters) - British Prime Minister Gordon Brown has offered to host Darfur peace talks, his office said on Sunday.

A spokesman said British officials have been in contact with the Khartoum government and rebel groups to stage a summit "as soon as practicable".

"We are doing this very much in conjunction with the United Nations and the African Union", he told Reuters.

"The Prime Minister is offering to hold all-party talks in London if that will facilitate progress to a lasting solution in Darfur."

International experts estimate some 200,000 people have died and 2.5 million been driven from their homes since mostly non-Arab rebels took up arms in Darfur five years ago.

Washington calls the violence genocide and the conflict has captured attention in the West, with Hollywood stars, sportsmen and world famous authors campaigning for an end to fighting.

Khartoum denies genocide, a term European governments are reluctant to use, and puts the death toll at 9,000, blaming the Western media for exaggerating the conflict.

"Like the thousands of people taking part in events across the world today I feel frustrated by this appalling situation and the slow progress," Brown said in a message on Sunday to mark the fifth anniversary of the conflict.

"But I am determined that we will not fail. Five years is more than enough for anyone to have to live with the sort of suffering that the people of Darfur have had to endure."

Protests around the world on Sunday to mark five years of war in Darfur are expected to draw thousands of people. Organised by an international coalition of activists and rights groups, the demonstrations will focus especially on the more than one million children caught up in the conflict.

In London, a group of children from Darfur are meeting International Development Minister Shahid Malik and a protest is being staged outside the Sudanese Embassy.

Harry Potter author JK Rowling is among celebrities calling for greater protection for children caught up in Darfur's war.