Prime Minister Gordon Brown has achieved a breakthrough in his mission to bring peace to the troubled African region of Darfur.

Mr Brown, who is giving a speech at the UN in New York and earlier met the organisation's secretary-general, Ban Ki Moon, held his first official face-to-face talks with President George W Bush on Monday.

Britain is due to table a Security Council resolution later, which officials expect to be approved, paving the way for a joint African Union and United Nations peacekeeping force to deploy to Darfur by October 1.

Mr Brown said: "Today is decision day for the United Nations to send an African Union and United Nations force of 20,000, to call on the government of Sudan for a ceasefire."

"We will work hard to deploy this force quickly. But we must be clear: if any party blocks progress and the killings continue, I and others will redouble our efforts to impose further sanctions," he said.

After months of hesitation, Sudan has agreed to the troop numbers but UN officials expect it will take a year to get the force in place. Khartoum also has to agree to allow individual units into the country.

In his speech at the UN, Mr Brown is demonstrating his determination to improve the situation for millions afflicted around the world.

The UN aims to halve the number of people living on less than $1 a day by 2015 as well as reducing child and maternal mortality, stopping the spread of Aids, TB and malaria, and halving the number of people without access to clean water and sanitation.

However, a report has shown that most of the UN's Millennium Development Goals, adopted at a summit in 2000, are far from being met.

Mr Brown is calling for companies and charities to get involved in the drive to meet the goals which Mr Ban said earlier this month would be a struggle to meet unless rich countries boost their international aid budgets.

Elsewhere, Mr Brown apologised for mistakes made in the run-up to the Iraq war during an interview in the US.