Several thousand anti-government demonstrators marched in Antananarivo Thursday in the latest demonstration in two weeks of anti-government unrest sparked by anger over power and water shortages in the impoverished Indian ocean island.

AFP reporters on the ground saw at least six people injured and a man left unconscious on the ground after he was chased and severely beaten by security forces, who used tear gas, rubber bullets and armoured vehicles to disperse the crowds.

"We're receiving troubling reports of continued violence against protesters by the gendarmerie," the UN's human rights office said in a post on social media Friday.

UN High commissioner for human rights Volker Turk "renews his call on security forces to desist from unnecessary force and to uphold the rights to free association and peaceful assembly," it said.

Madagascar's security forces on Friday recognised that it had taken "strict measures" as they claimed the protesters aimed to "terrorise the population" and "incite looting".

The United Nations said on September 29 that at least 22 people had been killed in the first days of protests.

Rajoelina has disputed the toll, saying on Wednesday that there were "12 confirmed deaths and all of these individuals were looters and vandals".

After initially adopting a conciliatory tone and dismissing his entire government, the president appointed a military officer as prime minister on October 6 and chose to make the first appointments in his new cabinet to the ministries of the armed forces, public security and armed police, announcing that the country "no longer needs disturbances".