Human-rights groups in Senegal, including the local branch of the UK-based Amnesty International, have condemned police violence during an opposition rally in which one person was killed.
Officers used tear gas and water cannons to break up the protest in the capital, Dakar, on Tuesday night, attended by an estimated 10,000 people in what until now had been one of Africa's most stable countries
Amnesty International and the Senegalese Human Rights League and African Assembly for the Defence of Human Rights said in a statement on Wednesday they "vigorously [condemned] deliberate violence perpetrated by police against peaceful, unarmed protesters".
The joint statement, drawing on witness accounts, said live bullets had been fired into the crowd. They also accused police of having "fired tear gas at medical vehicles."
Scores were injured and one man killed when a police lorry drove into the crowd. Police have denied it was their vehicle which killed a 32-year-old man.
The two rights groups called for an independent inquiry into the night's unrest.
Thousands of people were protesting against plans by President Abdoulaye Wade, 85, to seek a third term in office in February 26 polls in what the opposition has branded a "constitutional coup d'etat".
Al Jazeera's Barnaby Phillips, reporting from Dakar, said that students were rioting over the death of another student in demonstrations on Tuesday night in the centre of the capital.
"A cat and mouse game has been going on throughout the afternoon, with students rushing out the campus, hurling rocks to the police.
"There is an awful lot of frustration among young Senegalese about economic stagnation, the kinds of people who perhaps were very excited and believed all the promises when Wade came to power 12 years ago as an opposition leader."
More protests planned
Senegal's opposition pledged on Wednesday to press on with its campaign against Wade's ambitions for a third term.
Serigne Mbacke Ndiaye, the Senegalese presidential spokesman, dismissed the protests as a failure and evidence that Wade commanded wide support.
"If 13 candidates supported by nearly 70 political parties and civil society organisations only managed to mobilise 2,500 people, it proves Abdoulaye Wade holds a majority in Senegal," he said in a statement
However, Abdoul Aziz Diop, the June 23 (M23) opposition movement spokesman, said the rally was a success.
"Our capacity for mobilisation has not been contradicted, the movement achieved maximum mobilisation," he said.
Diop said a "crisis committee will meet today to evaluate the next step after the protest. But from now on we will take into account the repression by the government and develop a strategy against it".
In a statement, Ban Ki-moon, the UN secretary-general, has expressed concern about the rising tensions.
He urged "all political parties and national stakeholders to refrain from violence in the pursuit of their objectives and to pursue peaceful means to resolve all electoral grievances".
Megan Radford, a journalist based in Dakar, told Al Jazeera Tuesday's demonstration took some time to begin but thousands arrived later in the evening.
"People only started arriving late into the afternoon but within the next few hours, the number of protesters had increased dramatically," she said.
"I spoke to an older woman and asked her why she was there. She said that Wade needed to leave. She said she had a large family, and when I asked her if she was there for them she said: 'I am here for me, I am here for everyone!'"
A second death
Alioune Tine, a prominent rights activist and member of M23, said a second person was killed during the dispersion of the riot. However, this has not been be confirmed by authorities.
A ruling by Senegal's constitutional council that Wade was legally allowed to seek another term has sparked fury among opponents who accuse him of fiddling with the law to remain in power.
Wade says a constitutional amendment to presidential terms does not apply retroactively, which means the two terms he has already served cannot be taken into account and theoretically allows him to serve two more seven-year terms from 2012.
A policeman was killed in riots last Friday when the council gave Wade the green light, and another two people were killed in protests on Sunday in the northern city of Podor.
The US has urged Wade, in office since 2000, to allow power to pass "to the next generation" while observers have condemned the mounting violence in one of Africa's most vibrant democracies.
Senegal, which some see as a beacon of democracy among troubled neighbours, is the only country in West Africa not to have had a coup since the end of the colonial era.
Source: Al Jazeera and agencies