The letter was signed by celebrities and charities

The letter, also addressed to Chancellor Gordon Brown, was published in the Independent newspaper.

It praises the government for increasing funding to tackle world poverty and its commitment to reach a UN-set aid giving target by 2013.

But the letter urged the government to go further and cancel Third World debt.

"In 2005 as chair of the G8, the Commission for Africa, and the EU you will have a unique opportunity," the letter states.

"We're counting on you to lead rich countries to cancel Third World debts, deliver more and better aid that meets the UN target, and end unfair rules."

The group had previously written a letter to the government urging them to commit more money to foreign aid.

Mr Brown recently announced that development assistance would rise to �6.5bn - 0.47% of the UK's national income.

The UN wants countries to commit 0.7% of their national income in foreign aid by 2013.

The open letter was also signed by Coldplay's Chris Martin and actors Colin Firth, Joseph Fiennes and Dame Helen Mirren. It was also backed by a number of charities.

The letter gave examples of what the extra money will mean for those in need:

• Clean water for 14 million more people
  
• Education for two million more children
  
• Survival for 250,000 infants whose premature death can now be prevented

Film director and co-founder of Comic Relief Richard Curtis said: "Over the years, the British public has given hundreds of millions of pounds to charity to fight poverty and suffering abroad.

"At last, a government has matched the generosity and passion that people feel in the face of a world where 30,000 people still die unnecessarily of extreme poverty every single day.

"Now we all hope the UK will lead a massive crusade next year that could halve those deaths within a decade. It can be done. Bravo and onwards and upwards in 2005."

The letter was backed by six of Britain's leading aid charities: Data, Oxfam, Plan UK, Tearfund, Unicef UK and WaterAid.