Zimbabwe's main opposition party on Sunday claimed an early lead in elections, including in some rural strongholds of President Robert Mugabe, in an apparent effort to thwart any attempt to rig the vote count.

The head of the Pan-African Parliament observer mission said he was sure most results were known and warned against a delay of an official announcement of the outcome.

The Movement for Democratic Change said party leader Morgan Tsvangirai was leading the presidential race with 67 percent of votes, based on returns from 35 percent of polling stations nationwide. With three-quarters of Zimbabwe's population in rural areas where Mugabe garners most of his support, it was impossible to determine what those figures meant to the race.

Party secretary-general Tendai Biti told a news conference they based their claim on results from Saturday's balloting posted on the doors of polling stations overnight, which party election agents sent by mobile phone text messages.

"The people's victory is on course," Biti said Saturday night. "We have absolutely no doubt that we are winning this election."

People celebrated in the streets, giving each other the open-handed wave that is the opposition party's symbol. Mugabe's is a clenched fist.

In Harare's densely populated Mbare suburb, cars hooted their horns as opposition supporters sang and danced. "Give Tsvangirai his chance!" they sang.

But Hapisson Mate, a 23-year-old first-time voter, was worried: "Why are we not getting the results? It's very clear to me Mugabe wants to steal this election."

Police had tried to persuade the opposition leaders not to announce results, arguing it was illegal for anyone other than the Electoral Commission to do so. But the opposition party's lawyers said the information already was public.

The announcement defied a stern warning from the southern African nation's security chiefs, who already have said they would serve only Mugabe.

"We will not tolerate any such (unofficial election result) pronouncements as they have the effect of trying to take the law into their own hands thereby fomenting disorder and mayhem," they warned on Friday.

They and other government officials say they do not want to see a scenario similar to Kenya, where a delayed announcement of December election results led to a spontaneous explosion of violence. That vote count was so rigged no one knows who won. More than 1,000 people were killed in Kenya.

"I have no doubt that the large part if not all results are known. It is frustrating," Marwick Khumalo, head of the Pan-African Parliament observers, told South African Broadcasting Corp. TV.

Khumalo, who also observed the Kenyan elections, said the delay "creates anxiety" and has the potential of "upsetting a very peaceful electoral process".

At the hotel where the opposition held its news conference, Zimbabwe's Electoral Commission chairman, Judge George Chiweshe, was mobbed by reporters demanding to know when he would start announcing official results. Chiweshe said it was taking time because Zimbabweans, for the first time, were voting for president, the two houses of Parliament and local councilors, so four ballots have to be counted for each voter instead of one.

"This has been a more complicated election. We will be releasing the results as soon as we can," he said.

Other people gathered around to demand results, and Chiweshe was hustled, running, through the lobby by security agents, pursued by people shouting, "We want results."

Election observers who visited the commission's headquarters early Sunday said it appeared to have only a skeleton staff and seemed in no rush to release results.

"The regime is at a loss and it is taking its time deliberately," Biti charged, saying they were concerned by the delay.

If no presidential candidate wins 50 percent plus one vote, there will be a runoff.

Running against Mugabe are Tsvangirai, 55, who narrowly lost disputed 2002 elections, and former ruling party loyalist and Finance Minister Simba Makoni, 58. Makoni threatens to take votes from both the opposition and the ruling party in the elections, which hinged on the destruction of the economy with soaring beyond 100,5000 percent.

Biti said his party had won nearly all parliamentary seats in the two biggest cities, Harare and Bulawayo, which was no surprise as those are opposition strongholds. But he said they also had won in Mashonaland West and Masvingo districts as well as the northeastern town of Bindura, all areas where Mugabe has swept votes in the past.

Bindura, a rural mining and agricultural center, is home to the feared youth brigade of Mugabe's ruling party — tens of thousands of thugs known for beating up opposition supporters.

The elections presented Mugabe with the toughest challenge ever to his 28-year rule. Voting was generally peaceful, with Zimbabweans standing in lines for hours, but African observers questioned thousands of names on the official roll.

The 84-year-old Mugabe, in power for nearly three decades, dismissed rigging charges.

"I cannot sleep with a clear conscience if there is any cheating," he said Saturday after voting and promising to respect results. "If you lose an election and are rejected by the people, it is time to leave politics."

A parliamentary candidate for Mugabe's party in Bulawayo, Judith Mkwanda, reported two explosions outside her home that shattered windows just after midnight. Police said it was firebombed. No injuries were reported.

Tsvangirai's party said the home of one of its agents was set ablaze Saturday in northeast Zimbabwe.

The independent Zimbabwe Election Support Network's monitors reported a heavy police presence at polling stations, ostensibly to help illiterate voters and allowed under a belated presidential decree that breaks an agreement signed with the opposition. The opposition said it was intimidation.

Biti and his party have said their agents and supporters were barred from polling stations in several districts, ballot boxes were stuffed, and election rolls were inflated with dead or fictitious people.

Zimbabwe barred several international media organizations from its elections and observers traveling from the U.S. and EU.