Malawi's electoral commission has said that the number of votes cast in this week's presidential election exceeded the number of voters registered, hours after blocking the president's attempt to declare the poll "null and void".

The commission late on Saturday said it had suspended announcing results and ordered a physical re-count, with commissioner Chimkwita Phiri saying the number of ballots counted exceeded the number of voters registered.

The announcement came hours after the commission successfully sought a high court ruling against president Joyce Banda's declaration that the election was "null and void" and that she was ordering a new poll.

Banda said there were "serious irregularities" including multiple voting, ballot-tampering and a flawed computerised counting system.

I have never heard anywhere in the world where an opposition can rig an election. Peter Mutharika, leader of the opposition DPP,

"I am nullifying the elections, using the powers invested in me by the Malawi constitution," she said. A fresh election would be held within 90 days, she said, adding that she would not stand in the re-run.

The commission had earlier released preliminary results showing opposition Democratic Progressive Party candidate Peter Mutharika leading with 42 percent of the vote, followed by Banda with 23 percent. This was based on 30 percent of the total votes counted.

"Nothing in the constitution gives the president powers to cancel an election," said Mutharika on Saturday. "I have never heard anywhere in the world where an opposition can rig an election," he said.

On Friday, the Malawi's electoral commission said it had received 135 complaints of irregularities, which it was investigating before announcing the official results.

"We're committed to a process that's accurate and transparent. As far as we know, polling was free and fair in 99 percent of the centres and both local and international observers have commended the process," said a spokesman.