Dakar - Senegal's opposition on Thursday vowed new protests over President Abdoulaye Wade's bid for a third term as the veteran leader dismissed the deadly tensions as a "normal" pre-election phenomenon.

The June 23 Movement (M23) called for a prayer meeting in central Dakar on Friday for those killed during protests against Wade's controversial candidacy for a third presidential term in February 26 polls.

M23 also urged its supporters to "be ready for peaceful protests to be held across the country in the coming days."

The West has distanced itself from its erstwhile ally amid rising violence in what has long been one of Africa's most stable nations.

But the under-fire octogenarian president on Thursday underscored that "Senegal has a long tradition of elections... and peace has prevailed despite tensions noted by others.

"This situation, given that Senegal is approaching elections, is normal," he said, promising a "free and transparent" ballot.

UN rights chief Navi Pillay said she was disturbed by reports that police in Senegal had used "excessive force" against anti-government protestors.

M23 protests to force Wade to withdraw his candidacy have descended into riots, leaving four people dead since Friday when the country's highest court said Wade can run despite already having served two terms.

Wade argues he can serve another two seven-year terms from 2012 because a constitutional cap was only introduced in 2008, after his latest reelection.

On Thursday protesters marched peacefully in the northern city of Saint-Louis.