The United States is urging parties in Ethiopia to maintain a peaceful atmosphere in the country after general elections Sunday marked by fraud claims by opposition parties. Final results are not expected until June 8.

The United States is appealing for restraint by all of Ethiopia's political players while opposition allegations of harassment during the campaign and at the polls are investigated.

State Department Spokesman Richard Boucher said 17 teams of U.S. embassy observers joined personnel from the European Union and the Atlanta-based Jimmy Carter Center, including the former U.S. President himself, in monitoring the vote.

Mr. Boucher told reporters the initial reading from the monitors is that, while there were administrative and procedural irregularities, such as ballot shortages and slow-moving lines at the polls, it does not appear to fit a pattern of systemic fraud.

But he said opposition politicians have alleged intimidation and harassment in both the polling itself and the run-up to the election, and he urged calm as the claims are investigated.

"We expect the opposition, the majority party and the government to maintain a peaceful atmosphere and respect the outcome of the voting, and to refrain from violence at this juncture. We are concerned  about a decision by the government of Ethiopia to ban post-election demonstrations, and our embassy is monitoring that situation closely," he said.

The government said it was banning public protests for the next month to maintain order as vote-counting proceeds.  Provisional results are due by the end of the week and final returns by June 8.

The voting Sunday, which reportedly drew some 90 percent of registered voters to the polls, was only the  third full-scale election in the country's history.

Spokesman Boucher said if the opposition's fraud claims are substantiated, it would raise questions about the Ethiopian government's commitment to real democratic reform.

Early last month, the State Department expressed disappointment over Ethiopia's expulsion of staff members of three U.S. non-governmental groups helping prepare for the elections.

Last week, the U.S.-based Human Rights Watch accused Ethiopia's ruling party of large-scale political repression of the opposition in the southern Oromia state, the country's most populous region.

The charge was vigorously denied by government officials.

The ruling party of Prime Minister Meles Zenawi is claiming victory based on preliminary returns. But  opposition parties appeared to have sharply increased their numbers in parliament, among other things winning all or most seats in the capital, Addis Ababa.