UNITED NATIONS (CNN) -- The failure to release the results of last month's Zimbabwe elections could cause the situation in that country to deteriorate further with "serious implications" for its people, United Nations Secretary-General Ban Ki-moon warned Wednesday.
In unusually blunt remarks during a special U.N. Security Council session, Ban said he was deeply concerned about the uncertainty created by the failure to release the results of the March 29 elections.
Tensions have risen and violence has broken out in Zimbabwe after opposition candidate Morgan Tsvangirai declared victory over incumbent President Robert Mugabe a few days after the voting, based, the opposition said, on results posted outside polling stations.
Mugabe has been criticized for delaying the announcement of the results, with some saying he's stalling the process to remain in power.
Ban said he is watching and waiting "for decisive action" on the matter.
He added that if there is a second round of elections because no candidate reached the required majority to automatically win, it should be conducted in a fair and transparent manner. Ban said the United Nations stands ready to help.
His comments came during a Security Council session on the overall relations between the African Union and the United Nations, which was chaired by South African President Thabo Mbeki. South Africa is currently president of the Security Council.
Mbeki has sided with Mugabe on the election issue, saying it was not a crisis. Before the council convened, advocates for a change in Zimbabwe flew a plane near the United Nations trailing a banner that read, "Mbeki: Time to act, democracy for Zimbabwe."
British Prime Minister Gordon Brown urged the Security Council to send out a unified message on the matter.
"The democratic process depends on there being a democratic government. So let a single clear message go out from here in New York that we are, we will, be vigilant about human rights, that we stand solidly behind democracy and human rights for Zimbabwe," he said. "And we stand ready to support Zimbabweans build a better future."
The British leader said that based on the results posted at polling stations after the vote, "no one thinks ... President Mugabe has won this election."
The U.S. State Department also expressed concern Wednesday about "legitimate, credible reports" that Zimbabwe opposition figures are being harassed.
Spokesman Sean McCormack said those reports, while not specific, indicate supporters of the opposition Movement for Democratic Change are "being roughed up."
"It is quite disturbing," he said at Wednesday's daily briefing. "What is taking place in Zimbabwe now runs counter to the interests of Zimbabwean people who we believe have an interest in building a more prosperous, more democratic state."
According to a news release from the Crisis in Zimbabwe Coalition, more than 35 journalists, human rights activists and MDC supporters have been arrested since Tuesday, when the MDC called for a general strike.
The MDC called for the "mass stay-in" to continue until the government releases results from the presidential election.
The Crisis in Zimbabwe Coalition said arrests include Marvelous Kumalo, a recently elected member of parliament, and Frank Chikore, a freelance journalist. E-mail to a friend