The two factions of Zimbabwe's opposition party have reunited, and have called on President Robert Mugabe to concede defeat in last month's elections.

Movement for Democratic Change founder Morgan Tsvangirai and the leader of a former breakaway faction, Arthur Mutambara, held a joint news conference in Johannesburg, South Africa Monday.

Mr. Tsvangirai said the reunited factions have a majority in parliament. He said Mr. Mugabe should concede that he can not be president without controlling the legislature.

In a related development, Zimbabwe's electoral commission says a partial recount of results from the March 29 elections is complete, and that results from the country's presidential elections could be released this week.

World leaders are demanding that the commission release the results from the election, held nearly a month ago. The opposition says Mr. Tsvangirai defeated Mr. Mugabe and it accuses the president of illegally trying to hang on to power.

Electoral officials say they will invite the presidential candidates or their representatives to verify the results before they are released.

Results from Zimbabwe's parliamentary elections, also held last month, showed the opposition taking control of parliament for the first time since the country won independence from Britain in 1980.

The United Nations Security Council plans to discuss Zimbabwe's security situation on Tuesday.

The MDC and human rights groups have accused Mr. Mugabe'supporters of beating opposition activists as retribution for last month's election, and to intimidate voters should there be a presidential run-off.

Authorities detained more than 200 MDC activists in the capital, Harare, on Friday. Lawyers for the activists said Monday that a judge has ordered authorities to either release or charge the activists immediately.

Some information for this report was provided by AP and Reuters.