Johannesburg/Harare - As southern African leaders arrived in Zambia Saturday for an emergency summit on the election crisis in Zimbabwe pressure on President Robert Mugabe's neighbours to take a tough line with the aging leader was mounting.

Zambian President Levy Mwanawasa, chairman of the 14-nation Southern African Development Community (SADC), convened the extraordinary summit to try to resolve the standoff between Mugabe's party and the Morgan Tsvangirai-led opposition over presidential elections held two weeks.

The refusal of the state-controlled Zimbabwe Electoral Commission to release the official results of the March 29 vote has stoked tensions between supporters of the longtime rivals.

The Movement for Democratic Change (MDC) claims Tsvangirai won the presidential election outright and accuses Mugabe of withholding the results to rig them.

Mugabe's party claims neither Tsvangirai nor Mugabe took more than 50 per cent of the vote and says a second round of voting will be needed.

Former UN secretary general Kofi Annan Friday warned SADC leaders they had "a grave responsibility to act, not only because of the negative spillover effects on the region, but also to ensure that democracy, human rights and the rule of law are respected."

In a statement late Friday British Prime Minister Gordon said the patience of the international community over ZEC's refusal to release the election results was "wearing thin."

But in a sign that any speedy resolution of the impasse was unlikely Mugabe's party said he was boycotting the summit that Tsvangirai is attending because there was "no crisis in Zimbabwe."

Rural Affairs Minister Emmerson Mnangagwa and Foreign Affairs Minister Simbarashe Mumbengegwi would attend in his place, the party said.

As both sides became increasingly entrenched police Friday announced a ban on all political rallies in Harare until further notice while the MDC called for a nationwide work stayaway beginning Tuesday to press for the poll results.

In a statement Tsvangirai said Saturday's regional meeting was "an historic moment for SADC and a defining moment for Africa."

"We can show the world that we, Africa, can solve our own problems and safeguard democracy and the rule of law."

The summit was expected, as a minimum, to call for the urgent release of the election results.

Despite his party's defeat by the MDC in parliamentary elections and the ruinous state of the economy, Mugabe, 84, is seeking another five years in power.

Amnesty International has reported widespread violence against opposition supporters since the election in what the MDC claims is an attempt by Mugabe to subdue the population ahead of a possible runoff. (dpa)