Zimbabwe's legal experts have said President Robert Mugabe's unilateral call for end-of-July polls is illegal and he could be forced to overturn it at an upcoming regional meeting.
Veritas, an independent legal research group, said on Friday Mugabe had no power under the country's constitution to call for elections without the approval of the cabinet.
The goup's reaction came a day after Mugabe unilaterally declared July 31 as the date for presidential and parliamentary elections.
"In issuing an election proclamation, the president is obliged to act on the advice of cabinet. Quite obviously he did not do so. On that ground alone, the proclamation is legally void," the group said in a statement, warning SADC may rescind Mugabe's decision at its Saturday meeting in Maputo, Mozambique.
SADC - or the Southern African Development Community - brings together 15 countries, including Zimbabwe, and has been previously involved in charting the country's political roadmap.
Mugabe, in power since 1980, and Prime Minister Morgan Tsvangirai are in a unity government that was formed in 2009 after violent and disputed elections in 2008.
The legal group said the 89-year-old leader can only act on his own if he wants to dissolve parliament, but in this case he has allowed parliament to run until June 28, when it should expire after its current five-year term.
Tsvangirai, 60, claims Mugabe needs his consent on when to hold elections under the power-sharing deal.
Veritas said Mugabe had created a political crisis in unilaterally calling for polls.
It said once Mugabe has set an election date, amendments to electoral laws that critics say have led to vote-rigging in the past cannot be made as proposed in the nation's new constitution.
Mugabe invoked special presidential powers to by-pass parliament and fast-track changes to electoral laws a few hours before his notice announcing an election date.
But Veritas said the amendments to the electoral laws that Mugabe would have made are superseded by the election notice rendering them invalid.
"So whatever deficiencies there may be in the amendments, the election will have to be held in accordance with them," it said.
Tsvangirai, who won the 2008 first round of elections but failed to gain a majority to form a government, has repeatedly demanded reforms in the pro-Mugabe police and military widely blamed for state-orchestrated violence in previous elections.
He was forced to boycott the second round of voting, citing widespread intimidation and threats against his supporters.