Madagascar's opposition has vowed to continue its "struggle" to remove the president after at least 50 protesters were shot dead by police in the capital Antananarivo.

"I tell the people that their lives, their blood was lost. We cannot stop. The struggle continues," Andry Rajoelina, the opposition leader and former mayor of Antananarivo, said as he visited a hospital on Sunday.

Hundreds of people were reportedly injured when police opened fire on Rajoelina's supporters as they marched towards offices used by Marc Ravalomanana, the president.

"The people need change. What is the Ravalomanana's answer? Shots," Rajoelina said.

He said the fight would continue until the "final victory" and called for those responsible for the shootings to be arrested.

Heavy security

Heavily armed security forces patrolled the streets of the capital on Sunday, while the street to the presidential palace was closed. 

"I call on the security forces and the population to lend a hand in re-establishing calm and order in Antananarivo and in the whole of Madagascar," Ravalomanana said on national television on Saturday.

Security forces blocked the road to the presidential palace after the shootings [AFP]

Charles Rabemananjara, the prime minister, has announced a week-long extension of a night-time curfew that was already in force in the capital.

At the city's hospitals and mortuaries people searched lists of the dead and wounded for friends and relatives.

"I am looking for my roommate," Franck Raharisoa, a university student who was caught up in the shooting, said.

"They fired. I lied down and I lost him. I have been calling him since but only reaching his answering machine. I have looked at all the bodies in the morgue. He is not there."

Doctors said about 180 people arrived at the city's main Ravoahangy Andrianavalona hospital.

Opposition challenge

Tensions flared on Saturday after tens of thousands of Rajoelina's supporters hailed him as chairman of a "transition high authority" he had created himself in an attempt to remove Ravalomanana from power.

Rajoelina, who was dismissed from his position of mayor of Antananarivo after saying he was in charge of the country's affairs, said that all of the island's regions would be represented in the new body, while naming an associate as "prime minister".

The opposition leader has already launched a legal bid to to remove Ravalomanana through the two houses of parliament and the constitutional court, which has already declared it is not competent to rule on the matter.

He accuses the president of being a dictator and misspending public money.

Last month, at least 68 people died when rioting and looting broke out after a similar protest.