HARARE (Reuters) - Zimbabwe's runoff presidential election has been delayed and will now be held within 90 days of May 2, when official results of the disputed vote was released, Zimbabwe's government announced on Wednesday.

Results from the Zimbabwe Electoral Commission of the disputed March 29 election showed opposition leader Morgan Tsvangirai beat veteran President Mugabe in the presidential poll, but not by enough votes to avoid a run-off.

In a parliamentary election held on the same day, the ruling ZANU-PF party lost its majority to the opposition for the first time since independence from Britain in 1980.

In a special government notices gazette published on Wednesday, Justice Minister Patrick Chinamasa said:

"Not withstanding Section 110 of the Electoral Act, the period within which a second election for the office of the president is hereby extended from 21 days to 90 days from the date of announcement of results of the first poll."

Movement for Democratic Change spokesman Nelson Chamisa told Reuters, "But to us this is illegal and unfair. It is part of a programme to give Mugabe and ZANU-PF time to torment and continue a campaign of violence on the MDC."

The MDC accuses ZANU-PF of waging a campaign of violence and intimidation against its supporters as part of efforts to rig the vote. It says 32 of its supporters have been killed in the aftermath of the elections.