Amnesty International said: 'Political leaders must immediately address their supporters and demand they stop committing abuses. Police must fulfil their duty to respect and protect the right to peaceful protest.'

According to reports, the dead included a supporter of Haitian president Jean Bertrand Aristide's Fanmi Lavalas party who was shot and killed in an exchange of gunfire with the police, and Maxime Desulmant, an opposition demonstrator who was killed by gunfire from Aristide supporters.

Only one week on from the 200th anniversary of Haiti as a sovereign state, last year's growing political violence continues. In the run-up to the 1 January Bicentennial, Amnesty International had issued a plan of action calling on the authorities to guarantee that no human rights violations would be tolerated during the celebrations and urging political parties to control their supporters.

Opposition leaders have called for several days of strikes in the wake of yesterday's demonstration, during which journalists and radio stations were also said to have come under attack.

The organisation concluded: 'Amnesty International is deeply concerned about the near-incessant clashes between pro-and anti-government activists in Haiti, in which several people have lost their lives already this year. We are fearful of the human rights impact of this spiral of violence, and ask the authorities, with the co-operation of political parties, to immediately bring those responsible to justice.'