Gordon Brown said last night that the international community's patience with the regime of Zimbabwe's President Robert Mugabe's was "wearing thin".
In a statement, the Prime Minister said he could not understand why it was taking so long to announce the result of the 29 March presidential elections. It added that he was "appalled by the signs that the regime is once again resorting to intimidation and violence".
The statement comes a week before Mr Brown is due to speak to a United Nations Security Council debate in New York, which could be hijacked by the Zimbabwe crisis.
Thabo Mbeki, South Africa's President, whose country chairs the 15-nation council this month, will host Wednesday's public debate convened to discuss UN co-operation with regional African organisations. But a British diplomat said: "Zimbabwe will definitely be on the agenda."
The televised debate will provide an opportunity for Mr Brown and other leaders to keep up the pressure on President Mugabe by stating their positions on the Zimbabwean elections and on Mr Mugabe's future following today's summit of the Southern African Development Community (SADC). But, depending on the outcome of the summit, leaders could also consult privately. "Will SADC be tough enough with Mugabe to back him off coercion, and will the UN Security Council start engaging next week?" asked a British official. Britain has been active behind the scenes in the two-week stand-off since the elections, informing African partners the UK was ready to give aid once Mr Mugabe had left office.
Mr Brown held talks with President Mbeki last weekend and, according to one diplomat, agreed "with a heavy heart" to Mr Mbeki's request for more time for the situation to be resolved.