PM Morgan Tsvangirai accuses Robert Mugabe of frog marching Zimbabwe towards another 'illegitimate and violent' election

President invokes powers to bypass parliament and declare elections to be held by the end of July

President Robert Mugabe has been accused of “frog marching” Zimbabweans towards another “illegitimate and violent” election after unilaterally declaring 31 July as polling day.

Morgan Tsvangirai, his political rival and prime minister in the power sharing government that followed the last election, has opposed snap elections saying they would violate the country's new constitution.

Mr Tsvangirai, who was informed by letter of the election date warned that key reforms to the media, security services and voters' roll had not been carried out. He fears that the push for early elections aims to exploit loopholes that will allow his opponents to rig the election. The prime minister said the earliest legal date for an election was 25 August. He described the attempt to push through an early vote as “a clear, flagrant and fraudulent breach of our Constitution.”

Earlier in the day Mr Mugabe unilaterally changed several aspects of the election law including reducing the registration period, which began on Monday from 30 days to 17. Zimbabwe's highest court surprised observers in May by calling for elections to be held no later than the end of June despite a host of agreed reforms still waiting to be implemented. The 89-year-old Mr Mugabe is a past master of using procedure to throttle any challenge to his authority. The bulk of the reforms agreed to in peace talks five years ago, mediated by South Africa, have been hollowed out or entirely ignored.

The old political foes have been been locked in a dysfunctional unity government that was agreed under pressure from regional powers including South Africa in the aftermath of violent and disputed elections in 2008. Mr Tsvangirai won the first round of the last polls but withdrew from a run-off against Mr Mugabe after a concerted campaign of violence and intimidation against his supporters.

Despite delivering some comparative economic stability, Mr Tsvangirai's Movement for Democratic Change has had little influence over the courts, the media or the security services which are still controlled completely by the president's Zany-PF party. An extraordinary summit of regional leaders has been called to discuss the forthcoming elections but has twice been delayed to accommodate Mr Mugabe.

“It is now clear that President Mugabe called for the postponement in order to go to SADC with a done deal of an election date,” said Mr Tsvangirai. “Thus clearly, President Mugabe has sought to render the forthcoming SADC summit a dead rubber and a talk show.”