The charred remains of 37 people have been found in a shop in Madagascar, a day after it was burned and looted following an anti-government rally in the capital.

The discovery of the corpses on Wednesday brought to 39 the number of people killed in anti-government protests in Antanana-rivo, the capital, a day earlier.

Firefighters said the dead were suspected looters who were trapped in the shop as it burned down. 

"It is hard to determine the precise numbers because the bodies are badly damaged, and there are limbs scattered all over the place," a senior firefighter said.

The rally, called by Andry Rajoelina, the opposition leader and the city's mayor, turned violent when protesters looted and set fire to a state radio building and ransacked a private TV station and business premises belonging to Marc Ravalomanana, the president.

Stirring tension

More than 40,000 opposition supporters demonstrated peacefully on Wednesday.

Rajoelina, whose private TV station was closed by the government in December, called on them to stage a general strike and accused the president of running Madagascar as a dictatorship.

Jean Ping, a diplomat for the African Union (AU) said he was "deeply concerned by the prevailing political tension and the risk it poses to the stability of the country".

He urged those involved to end the crisis through "dialogue and respect for constitutional order and legality".

The president has accused his rival of stirring tension in an effort to overthrow the government.

Both parties have called for calm but have yet to initiate talks to resolve the impasse.

The political crisis risks harming Madagascar's image as a popular tourist destination and dissuading foreign investors keen to exploit its reserves of oil and minerals.