Security forces are out on the streets of the capital amid a tense calm
Madagascar's defence minister has resigned after police shot dead 28 opposition protesters at the weekend.
Cecile Manorohanta said her conscience could not endure the bloodshed. She was replaced by the chief of military staff, Mamy Ranaivoniarivo.
It comes amid a bitter power struggle between President Marc Ravalomanana and opposition leader Andry Rajoelina.
Up to 5,000 people held a memorial for the dead protesters in Antananarivo on Monday and later dispersed peacefully.
Mr Rajoelina on Saturday organised a large rally attended by some 20,000 people during which he announced a "transition authority" and named his own prime minister.
In addition to some 28 people who died as security forces opened fire on demonstrators marching towards the presidential compound, more than 200 people were wounded.
The minister, once a close ally of the president, read out a resignation statement on the private radio channel Antsive on Monday.
She said: "In this period of political crisis, I extend my condolences and moral support to the families who suffered losses.
"As a mother, I do not tolerate this violence. It was agreed at government level that the security forces were meant to protect the population and its property."
Meanwhile, Haile Menkerios, the UN assistant secretary general for political affairs, expressed concern at events in Madagascar after meeting President Ravalomanana on Monday.
He said UN Secretary General Ban Ki-moon felt "extreme sadness" over Saturday's deaths and was calling for those responsible from both sides to be brought to justice.
Opposition leader Andry Rajoelina is a 34-year-old former DJ
The UN envoy is also meeting Mr Rajoelina.
The weekend's rally followed last week's dismissal of Mr Rajoelina as mayor of the capital, Antananarivo.
The 34-year-old former DJ has accused President Ravalomanana of being a dictator and of misspending public money.
The president, who is also a former mayor of Antananarivo, has accused the opposition leader of trouble-making.
Saturday's bloodshed brings to more than 100 the death toll since anti-government protests erupted at the end of January.
Madagascar, the world's fourth-largest island, has become a destination for tourists as well as foreign companies, searching for oil, gold, cobalt, nickel and uranium.