Christine Razanamahasoa, who leads a mediation group to find a way out of a political crisis that has raged for weeks, said the current situation in the country did not allow for a free and credible vote to be held on November 16.
The mediation group "strongly demands that authorities suspend the presidential election scheduled for November 16," Razanamahasoa told a press conference in Antananarivo.
She said this was to ensure "peace" and "harmony" in the country, where political tensions have been running high in the run-up to the vote, which was already postponed by a week.
But a spokeswoman for Madagascar's outgoing president Andry Rajoelina called the request a "far-fetched idea."
"There's no reason why the elections shouldn't be held on November 16," Lalatiana Rakotondrazafy told AFP.
The country's laws do not provide for the "suspension" of a vote and any such decision would require government approval.
The Indian Ocean island nation has been shaken by a fierce battle between President Andry Rajoelina, who is running for re-election, and most opposition leaders.
Eleven out of 13 opposition candidates have led near daily, unauthorized marches in Antananarivo, for more than a month, protesting at what they have called an "institutional coup" that favors the incumbent.
The demonstrations have been regularly met by a strong police presence.
Numerous people were injured on Wednesday as police dispersed yet another protest.
Earlier this week, a presidential candidate was detained at another rally.
The European Union, the United States and other members of the international community signed a joint statement on Thursday expressing their "deep concern following the violent incidents of recent days."
They had previously said they were following the preparations for the elections with "the utmost vigilance" and denounced the excessive use of force against the opposition.
The statement urged "all parties involved to exercise the utmost restraint, engage in peaceful dialogue and show a sense of responsibility."
Some 60 Madagascan civil society organizations and trade unions have called for the "cancellation" of the first round vote, warning of an "even harder crisis" if the election were to go ahead.
Voters in Madagascar were initially due to head to the polls on November 9, but the top court in October ordered that elections be postponed after another presidential candidate was injured during a demonstration.
The date for a potential second round on December 20 was kept unchanged.
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