The 53-member Commonwealth, which includes a number of corruption-hit nations, would have a "lively debate" on the subject at its three-day gathering in Malta, Obasanjo told the summit's opening session on Friday.

"Corruption has been one of the major sources of underdevelopment, instability, conflicts, illegitimization of leadership and government structures...," said Obasanjo, who hosted the last summit in 2003.

"We need to adopt a zero tolerance policy to this cankerworm at the local and international levels," he said.

"For this to happen, cooperation between developed and developing countries is essential," added the Nigerian leader, who also chairs the African Union.

Obasanjo has sought to crack down on graft since he came to power in 1999, with several top officials including ministers, the head of police and a senate president facing prosecution in the past months.

Stolen assets

Obasanjo said Commonwealth Secretary-General Don McKinnon would be presenting the summit with "proposals aimed at facilitating the recovery of stolen assets and their return to their country of origin."

"Corruption has been one of the major sources of underdevelopment, instability, conflicts..."

Nigeria's President Olusegun Obasanjo

He also cited the need for "clear and strong sanctions against the misuse of public funds" and increased cooperation "in every respect" among nations to tackle graft as important steps to fight corruption.

Member-states were also urged "as a matter of urgency" to sign up to the UN convention against corruption, Obasanjo said.

The convention, due to come into force next month, outlines several areas of action to combat graft through legislation and international cooperation.

Progress made

London, on the other hand, believes progress is being made on tackling corruption, Tony Blair's official spokesman told reporters travelling with the British prime minister, who,too, is attending the summit.

There was "increasingly an emphasis on good governance and on transparency" by organsiations such as the African Union and the Group of Eight (G8) industrialized countries' club, the spokesman said.

Obasanjo's appeal comes as a series of Commonwealth leaders grapple with corruption scandals at home, including South African President Thabo Mbeki, who fired his deputy president, Jacob Zuma, in June over allegations of graft, in a case that has thrown the governing party in crisis.

Along with corruption, a main theme of the summit is combating poverty, notably through trade.