HARARE, Zimbabwe - Zimbabwe's High Court rejected an appeal Monday for the immediate release of presidential election results, dashing hopes for an end to a paralyzing political crisis and prompting the opposition to call a nationwide strike.

Opposition leader Morgan Tsvangirai says he won the March 29 election outright and has accused President Robert Mugabe of holding back the results to try to maintain his 28-year grip in power. Independent tallies show Tsvangirai won, but did not receive enough votes to prevent a runoff.

Tsvangirai's Movement for Democratic Change had hoped the court -- though stacked with Mugabe loyalists -- would force the election commission to release the results after a 16-day wait. The commission, which published results for parliamentary and local elections within several days of the election, said it can't release the presidential results until it investigates electoral anomalies.

In rejecting the opposition petition, the court ruled that the commission's explanation was "legally valid," and said the electoral body "has not strayed from the law."

Government spokesman Bright Matonga praised the ruling and dismissed charges the court was biased.

"The electoral commission should be allowed to do its job," he said.

Tsvangirai accused the election commission of working for the ruling party.

"Now, for the next three or four weeks, (the commission) will drag the time, while people get beaten and while a new electoral environment is being created," he told South Africa's independent e-tv station.

The opposition and human rights groups said ruling party militants have been waging a campaign of violence against opposition supporters ahead of a possible second round of voting.

Zimbabwe Lawyers for Human Rights said it had documented at least 130 attacks on opposition or independent poll monitors. Two people were killed and 29 hospitalized with serious injuries, director Irene Petras said.

The MDC called a nationwide strike for Tuesday in what would be the first major protest since the election.

The police have banned all political rallies, and opposition officials said Tuesday's action would be a quiet "stayaway," not a raucous strike complete with street protests.

"People are not going to go to work. They are going to be in their homes, expressing their dissatisfaction," MDC spokesman Nelson Chamisa said.

Past strike calls have been met with resistance by impoverished workers, who can't afford to lose even one day's wage in an economically ravaged country suffering 80 percent unemployment.

Meanwhile, opposition officials said violence was spreading.

Looting and arson attacks since Thursday in the northeastern Mutoko district -- a former ruling party stronghold that voted for the opposition -- have forced scores of villagers to flee their homes, the MDC said Monday.

Armed assailants broke into the home of a woman who had worked as an MDC polling agent and slashed her arms with knives as they interrogated her, the party said in a statement. Another was attacked with an ax, the party said. Medical staff at a Harare clinic said they treated several people from the area for broken bones, cuts and severe bruising.

State Department spokesman Tom Casey repeated the U.S. call for the Zimbabwean electoral commission "to let the votes be counted, to release those results, and to do so immediately."

He said that as long as the electoral commission refuses to release the results, "the situation is going to remain tense, and their failure to do so only raises more suspicions about what really happened in the process of that vote-counting."