Chancellor Gordon Brown and International Development Secretary Hilary Benn are leading a drive to boost the rich world's aid to education in developing countries.
The two ministers are attending a Brussels conference to highlight the £5.5 billion-a-year funding gap which needs to be filled if the United Nations Millennium Development Goal of getting all the world's children into primary education by 2015 is to be met.
And they will appeal to the private sector to make its contribution, alongside state aid, to helping educate the world's poorest children.
Some 77 million children currently go without primary education, and 75 countries are in danger of missing the Millennium Goal if more aid is not made available.
Mr Brown and Mr Benn announced last year, during a visit to Mozambique, that Britain will spend £8.5 billion over the coming 10 years to help poor countries provide primary education.
While no further cash pledges are expected from the UK on Wednesday, Mr Benn is due to give details of which countries will benefit from the money.
And he will warn that time is tight if the Millennium Goal is to be met.
In order to complete a full six-year primary education by 2015, tens of millions of children will have to start school by 2009.
Wednesday's event brings together governments from the rich and developing worlds, non-governmental organisations, international donors and the private sector under the banner Keeping Our Promises on Education.
Hosted by the European Commission and co-convened by the World Bank and the UK Government, it follows an earlier agreement in Singapore in September 2006 by Mr Brown, EU development commissioner Louis Michel and Paul Wolfowitz, President of the World Bank.
