By Deborah Haynes

LONDON, Jan 4 (Reuters) British finance minister Gordon Brown urged rich nations today to help ensure all the world's children had access to education within 10 years, saying failure to do so could fuel Islamist extremism.

''Education could be the greatest gift the richest nations make to the poorest,'' Brown, widely tipped to succeed Prime Minister Tony Blair later this year, wrote in an article for the Guardian newspaper.

Failure to act would enable madrassas ''created by religious extremists, offering free education but fundamentalist indoctrination'' to fill the void, said Brown, drawing on his experiences during a trip to Nigeria last year.

''Today education for all makes not just moral and economic sense, but strategic sense too,'' he said.

Brown's comments, his first political intervention of 2007, were made as attention focused on his expected bid to take over from Blair, who has pledged to step down this year.

''This year marks the 200th anniversary of Britain voting to end the slave trade. There could be no better commemoration than to abolish all child labour, and ensure that all young children go to school,'' Brown wrote.

''I want every parent, student and school in Britain and the developed world to become campaigners, calling on every government to give every child access to schooling.'' Brown, pushing for universal education to be achieved within a decade, said he and International Development Secretary Hilary Benn were publishing a pamphlet telling teachers and pupils about their ''Education for every child'' initiative.

The move -- helping British schools to build links with developing countries, including teacher exchanges -- would benefit 10 million children, he said.

Britain had already pledged 8.5 billion pounds (.76 billion) over 10 years -- enough for 15 million school places -- but more needed to be done, Brown said.

He said 22 African countries had committed themselves to developing plans in the last few months to enable their children to complete primary education by 2015.

''The cost is not prohibitive,'' said Brown, adding an extra 10 billion dollars a year by 2010 was probably the most cost effective investment the world could make.

REUTERS PDM BS1014