Once elected Secretary-General, he sought to revitalise the world body's peacekeeping efforts.

His first step was to "shake the house" with a highly critical report in which he warned: "We are perilously near to a new international anarchy."

With the 1982 Israeli invasion of Lebanon, and with conflicts raging in Afghanistan and Cambodia and between Iran and Iraq, he complained to the General Assembly that UN resolutions "are increasingly defied or ignored by those that feel themselves strong enough to do so."

"The problem with the United Nations is that either it's not used or misused by member countries," he said in an interview at the end of his first year in the post.

During his decade as UN chief, Perez de Cuellar would earn a reputation more for diligent, quiet diplomacy than charisma.

In July 1986, Perez de Cuellar underwent a quadruple coronary bypass operation, putting in question his availability for a second term. From the outset, Perez de Cuellar had insisted that he would be a one-term secretary-general.

But he did come back for a second term after a groundswell of support for his candidacy, including a conversation with President Ronald Reagan, who - in the words of the UN chief's spokesman - expressed "his personal support for the Secretary-General."

"Just about all the Western countries have told him they'd like to see him stay on," a Western diplomatic source said at the time. "There is no visible alternative."

Perez de Cuellar's diplomacy helped bring an end to fighting in Cambodia and the 1980-88 Iran-Iraq war, and the withdrawal of Soviet troops from Afghanistan.

After leaving the UN, Perez de Cuellar made an unsuccessful bid for Peru's presidency in 1995 against the authoritarian leader Alberto Fujimori, whose 10-year autocratic regime crumbled in November 2000 amid corruption scandals.

At the age of 80, Perez de Cuellar emerged from retirement in Paris and returned to Peru to take on the mantle of foreign minister and cabinet chief for provisional President Valentin Paniagua.

His impeccable democratic credentials lent credibility to an interim government whose mandate was to deliver free and fair elections. Eight months later, newly elected President Alejandro Toledo asked him to serve as Ambassador to France.

Perez de Cuellar turned 100 in January and on his birthday Antonio Guterres, who currently heads the UN, said he was an inspirational leader for the world body.

"On this momentous occasion, we at the UN draw on his example for inspiration & are deeply grateful for his many contributions and achievements as Secretary-General," Guterres wrote on Twitter.

Perez de Cuellar's remains will lie at the Peruvian foreign ministry before burial on Friday, his son said.