HARARE, ZIMBABWE - Zimbabwe's opposition accused President Robert Mugabe's regime on Friday of stepping up a crackdown by arresting its leader's lawyer ahead of a key summit on the country's post-election crisis.

"As a party we feel this is a sustained effort on the part of the authorities against people who assist the MDC," Movement for Democratic Change spokesman Nelson Chamisa said after the arrest of lawyer Innocent Chagonda.

"This is an onslaught which is not only happening in the rural areas, but even in the civil service as people who are perceived MDC supporters are being intimidated."

His comments came as Mugabe and opposition leader Morgan Tsvangirai prepared to lock horns at a weekend summit of southern African leaders aimed at sorting out Zimbabwe's election mess.

Regional leaders were converging on the Zambian capital Lusaka for Saturday's extraordinary summit of the Southern African Development Community to consider the crisis.

The prospect of bitter enemies Tsvangirai and Mugabe facing off over the conference table in Lusaka became real Thursday when both men's parties confirmed they would attend.

Tsvangirai met the same day in Pretoria with President Thabo Mbeki of South Africa, officials said. Mbeki, the regional heayweight, has come under fire for failing to condemn the long delay in announcing the result of the presidential election.

"The meeting went well. The details of it are not at this stage for public consumption," MDC spokesman Nqobizitha Mlilo told AFP, giving the first news of the meeting on Friday.

As international pressure mounts for Zimbabwe's poll results to be released amid opposition claims Mugabe might use violence to cling to power, Mbeki has stuck to his policy of quiet diplomacy, saying the situation was "manageable."

Southern African leaders have been heavily criticised over their traditional reluctance to criticise Mugabe, who has presided over his country's economic demise during his 28-year rule, which began with independence in April 1980.

Mugabe has often bridled at any kind of outside intervention, blaming the country's economic woes on a limited package of Western sanctions imposed after he allegedly rigged his 2002 re-election.

The former British colony now has a six-figure inflation rate and unemployment is beyond 80 percent, while average life expectancy stands at 37 years.

Thirteen days on from the country's presidential election on March 29 there has still been no announcement on the outcome, and while Mugabe's ruling party says there must be a run-off, the opposition says its man won outright.

A legal bid by the opposition to force Zimbabwe's electoral commission to declare the result is still under consideration by a judge and no decision on the matter is expected until Monday, at the earliest.

Not only is the ruling party contesting enough seats in the simultaneous parliamentary elections to overturn a slim opposition majority, but it has also demanded a total recount of the presidential vote.

Mugabe's ruling Zimbabwe African National Union - Patriotic Front (ZANU-PF) has accused the commission of massive counting anomalies and arrested 15 election officials for suspected fraud.

Three were sentenced Thursday to one week in prison or a fine of eight million Zimbabwe dollars (266 US dollars, or 23 cents on the more realistic parallel market) after failing to report a missing ballot box, the state-run Herald reported. --AFP