Thousands of Argentines swayed to protest songs Friday at an early morning vigil marking the 30th anniversary of a military coup that ushered in the country's Dirty War.

The gray-haired Mothers of the Plaza de Mayo took center stage at the rock concert-styled rally, wearing the trademark white handkerchiefs of their long human rights struggle.

"Thirty Years of Life Defeating Death!" and "Not One Step Back!" read large banners strung alongside black-and-white photographs of hundreds of "desaparecidos" — Spanish for the "Missing" victims of the seven-year dictatorship and its bloody crackdown on dissent.

It was just after 3 a.m. on March 24, 1976, that coup leaders announced they had toppled the government of Maria Estela Martinez de Peron, widow of the former strongman Juan Domingo Peron. She was flown away by helicopter from the pink Government House, steps from where the rally was held Friday on the Plaza de Mayo.

The junta would remain in power until 1983, leaving a trail of nearly 13,000 now officially listed dead or missing during the era. Human rights groups put the toll for a systematic crackdown on dissidents, now known as the Dirty War, at nearly 30,000.

Many of those in the crowd on Friday were youths born well after the coup,. They waved Argentine flags and leftist banners of red stars and clapped to vintage protest songs of folklore artists. Two large screens projected old newsreel clips of the former junta leaders and armored cars in the streets of Buenos Aires.

Blocks away from the plaza, giant enlargements of photographs of the victims were projected onto the capital's famous Obelisk monument. One photo a second was being projected on the smoothly chiseled granite of the towering Buenos Aires spire through the early dawn hours — a display of 3,600 pictures in all. The memorial was to conclude at the exact moment an announcer broke in on national radio with "Comunicado No. 1" declaring the constitutional government's overthrow.

The rally was led by Hebe de Bonafini, a leader of the most outspoken wing of the Mothers of the Plaza de Mayo — who have long demanded an accounting for missing sons and daughters.

Friday was the first time the anniversary was a national holiday.

President Nestor Kirchner was to give a speech and Argentina's foreign minister, Jorge Taiana, planned to visit the main Navy Mechanics School torture center. A large march was planned Friday evening.

Justino Carrea was among several former victims and victims' relatives who relived their experiences on television programs and in newspaper coverage blanketing the anniversary.

He recounted being picked up by security forces and whisked away to torture sessions.

"We can't have vengeance but we must have justice," he said of calls to reopen human rights cases before too many more years elapse. Noting that Congress recently repealed amnesty laws shielding officers from prosecution since the 80s, he said: "Now we must have the law, 100 percent of it."

Scores of former officers and others could be called back to courts to testify as a result of last year's repeal of those 80s-era amnesties. Kirchner's center-left government has vowed to reopen old files.