People across Argentina have marked the anniversary of the 1976 coup that unleashed a wave of repression in which tens of thousands of dissidents "disappeared."

Argentinians held a Day of Remembrance for Truth and Justice for the estimated 30,000 victims of the coup-installed military dictatorship's so-called national reorganisation process.

As part of the clampdown, better known as the dirty war, supporters of former president Juan Perón and his third wife Isabel, who was president from 1974-76, were rounded up and tortured alongside Marxists and socialists.

Current President Cristina Fernandez paid homage to her late husband Néstor Kirchner, who was instrumental in scrapping an amnesty law during his own presidency so that dirty war criminals could be prosecuted.

Thousands rallied in Buenos Aires's Plaza de Mayo, while earlier some blocked a main road to make their cry for justice heard.

Ministers flocked to the city's north to celebrate the 10th anniversary of the transformation of the former Navy School of Mechanics torture centre into a human rights museum.

Estela de Carlotto, the leader of a human rights group dedicated to finding the true identities of babies illegally snatched from their parents and adopted by families with ties to the military during the regime, was among the guests.

"We will carry on fighting for the dreams of our children that our grandchildren will be rescued," she said.

Five other former detention centres were reopened as museums across the country , taking the total number to nearly 70.