Gordon Brown yesterday issued his sternest warning yet to Robert Mugabe that the world would not allow Zimbabwe's elections to be "stolen" by the African leader.

As the former British colony's annual inflation rate hit a record 165,000%, the Prime Minister rallied the international community to defend the cause of democracy in Zimbabwe and help its people create a better future for themselves.

Addressing the United Nations Security Council in New York, Mr Brown sought to internationalise the pressure on Mr Mugabe when he said: "No-one thinks, having seen the result at the polling stations, that President Mugabe has won this election. A stolen election would not be an election at all. The credibility of the democratic process depends on there being a legitimate government.

"So let a single message go out from here that we are and will be vigilant for democratic rights and that we stand solidly behind democracy and human rights for Zimbabwe and we stand ready to support the Zimbabwean people build a better future."

The UN session was chaired by Thabo Mbeki, the South African President, who listened impassively to Mr Brown's remarks, having earlier pulled out of bilateral talks with the Prime Minister. British officials played down the apparent snub, saying the meeting had been cancelled because Mr Mbeki had been "running late".

On Saturday, after discussions with Mr Mugabe, who dismissed Mr Brown as an irrelevant "tiny dot", the South African President - one of the few international figures to have some influence on his neighbour - insisted there was "no crisis" in Zimbabwe, where, in addition to the world's highest inflation rate, eight out of 10 people are out of work, there are chronic food shortages and a quarter of the population has fled the country as economic refugees.

Mr Brown's fears were shared by Ban Ki Moon, the UN Secretary General, who spoke of his "deep concern" at the uncertainty that had been created by the failure of the Zimbabwean authorities to announce the presidential election results more than two weeks since polling took place. "The situation could deteriorate further with serious implications for the people of Zimbabwe," warned Mr Ki Moon. "If there is a second run of elections, they must be conducted in a fair and transparent manner with international observers," he added.

The Prime Minister is seeking to get the UN to play a bigger role in challenging Mr Mugabe, who simply dismisses criticism from Britain as the old colonial master seeking to re-exert its former control.

In South Africa, there was growing division over what should be done with Zimbabwe as Jacob Zuma, leader of the ruling party, widened his disagreement with Mr Mbeki, insisting anxiety was increasing by the day over a post-election deadlock in Zimbabwe.

In a speech, Mr Zuma said: "The region cannot afford a deepening crisis in Zimbabwe. The situation is more worrying now given the reported violence that has erupted."

He ousted Mr Mbeki as leader of the African National Congress last December and has moved gradually to increase his influence at the expense of his rival. "We once again register our apprehension about the situation in Zimbabwe. The delay in the verification process and the release of results increases anxiety each day," he told South Africa's Chambers of Commerce.

In Harare, the apparent procrastination continues. A judge adjourned a hearing until today about an application from the Opposition MDC to block a recount of all votes cast in 23 out of 210 constituencies in the March 29 parliamentary and presidential elections.

The MDC, which insists it won the election, claims a proposed recount is simply another tactic by Mr Mugabe to delay the election results while he orchestrates a campaign of militia violence to intimidate opposition supporters. The High Court has already refused to order the Zimbabwe Electoral Commission to release the presidential result.

Human rights groups say independence war veterans and other pro-Mugabe militia have organised systematic violence to try to ensure victory in a probable runoff.

A non-governmental agency called Zimbabwe Doctors for Human Rights said yesterday it had treated 173 victims of organised violence and torture from March 29 to April 14. It did not say who the victims or perpetrators were.