|Protesters say Preval should hand over authority to a provisional government [Reuters]
Protesters in Port-au-Prince, Haiti's capital, have set up burning barricades and are calling for Rene Preval, the country's outgoing president, to leave office immediately.
Around 200 protesters threw stones at police and UN peacekeepers on Monday, witnesses said.
Riot police fired some shots in the air to disperse the demonstrators, who shouted "Preval must go" and set fire to tyres and piles of rubbish outside the presidential palace.
Sebastian Walker, Al Jazeera's correspondent in Port-au-Prince, described the situation on the streets as "tense and unpredictable".
"We've seen police firing tear gas and shots in the air, protesters burning tyres and setting up barricades, but we have not seen the kind of numbers that might have had immediate consequences for what happens politically," he said.
Preval's mandate formally ended on February 7, but he has parliamentary approval to stay on until a decisive second round of the presidential elections can be held on March 20.
While Preval's parliamentary stamp of approval runs out on May 14, however, some opponents have called for him to step down in favour of a provisional government.
Fritz Longchamp, Preval's chief of staff, confirmed that the incumbent president had received the three-month extension.
"He will stay in office until May 14. He will not leave today," Longchamp told the Associated Press news agency on Monday.
The US and other nations have signalled that they agree with Preval's decision, as his departure would leave a power vacuum at the top of the Haitian government.
"We have seen over the last few weeks a very serious political crisis, following on from the widespread irregularities that happened during Haiti's election back in November," Walker said.
Preval has been at the centre of controversy over the presidential elections.
Last week, election authorities decided to eliminate Jude Celestin, a Preval-backed candidate, from a presidential run-off.
The move came after foreign governments challenged the contention that Celestin had won enough votes to qualify for the poll.
"We've seen widespread demonstrations pretty much ever since voting day happened," said Walker.
"A lot of the protesters are asking for the election to be annulled and held again, certainly they're not happy with the current government.
"The international community is very concerned that there is a degree of stability ... so they seem to be happy to have Preval stay on until the second round of the election happens in March."
Mirlande Manigat, the first-placed candidate, will now take part in a run off against Michel Martelly, a popular singer, in the final presidential election next month.
The final count naming Haiti's next president is expected on April 16.
Meanwhile, Jean-Bertrand Aristide, the former Haitian president who has been living in exile in South Africa, was issued with a passport by the Haitian government on Monday, an official said.
"The passport was issued on Monday. All the formalities have been completed," the official said, asking to remain anonymous, adding that the document had been handed over to Ira Kurzban, one of Aristide's lawyers.
Aristide moved to South Africa in 2004 after he was ousted as president.
"Aristide's return would shake things up politically and could destabilise the shaky resolution to the country's stalled political process," our correspondent said.