The United Nations is to reduce its presence in East Timor in spite of Security Council members' reservations about the new administration in Jakarta.

"We are very concerned that political instability in Jakarta has weakened efforts to initiate the establishment of an ad hoc tribunal for the prosecution of serious crimes committed in East Timor," said Alistair Harrison, speaking as the UK's chargi d'affaires,at last week's open meeting of the Security Council on East Timor.

"We very much hope that the recent change in Indonesia's political leadership will result in greater progress on this front. We call on the new Indonesian government to fulfil its obligations to make early progress in this area."

In a closed meeting ahead of the open debate, ambassadors were even more critical of Megawati Sukarnoputri, Indonesia's new president, and cautioned against giving the impression that the UN will leave East Timor to manage on its own any time soon. "The last thing we want to do at the moment is send a signal to the Indonesians that all is well and the UN is stepping back," said one western diplomat.

The US and France have been especially active in pushing the UN for an exit strategy for the 8,000-member peacekeeping force. "For the US and France, it's about general UN mandates and budgets and not having inflated operations that last for ever," the diplomat said.

David Malone, president of the International Peace Academy, said: "Scope for creative funding for UN peacekeeping is very limited. This is not the World Bank's responsibility or that of bilateral donors. This really is a core UN function."

Kofi Annan, the United Nations' secretary-general, said in a report that UN battalions stationed in central and eastern regions could be reduced as long as the security situation remained stable. Sergio Vieira de Mello, the UN's administrator for East Timor, said the reductions could come before East Timor's independence. Both men said that the UN's pullout would be gradual and that the organisation would continue to play a role in East Timor after independence.

The exact date of East Timor's independence is under debate. Mari Alkatiri, head of the leading party, Fretilin, says this should occur on November 28, the date Fretilin declared independence in 1975 before the former Portuguese colony was overrun by Indonesia. But he said the precise date would be a matter for East Timor's constituent assembly, a de facto parliament to be formed after elections on August 30, to decide.

Mr de Mello argued that independence should be delayed until the spring of next year. The constituent assembly needed time to formulate a constitution.

Human rights groups have been especially critical of Mrs Megawti's lack of willingness to crack down on Indonesian militia leaders. Eurico Guterres, who is wanted by the UN for war crimes, joined Mrs Megawati's party in 1999 after fleeing East Timor. He now serves as the head of the party's paramilitary branch in Jakarta.

Nevertheless, Jose Ramos Horta, the foreign affaires minister in East Timor's transitional government, said he hoped Mrs Megawati would resist the influence of Indonesia's hardline military factions.

[Carola Hoyos in New York and Joe Leahy in Dili]