BUENOS AIRES (Reuters) - The last leader of Argentina’s 1976 - 1983 “dirty war” military dictatorship, Reynaldo Bignone, died in a military hospital on Wednesday, Argentina’s state-run news agency Telam said.

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Bignone, 90, had been serving out jail sentences for conspiring to kidnap and kill opponents during his July 1982 to December 1983 rule.

His death closes a brutal chapter in Argentina’s history, during which rights groups say military rule was responsible for “disappearing” - a euphemism for kidnapping and murdering opponents - some 30,000 people.

Argentina started its transition to democracy in 1983 with an October election called by Bignone.

He was one of 15 former military officials found guilty by an Argentine court in 2016 of conspiring to kidnap and assassinate leftist dissidents as part of the Operation Condor program.

Dictatorships in Argentina, Chile, Uruguay, Paraguay, Brazil and Bolivia coordinated to hunt down and kill exiled opponents in the 1970s and 1980s.

Argentina’s first military leader Jorge Rafael Videla, who took over after a 1976 coup and ruled until 1981, died in 2013. Military leaders at the time said the crackdown they oversaw was necessary for Argentina to confront left-wing guerrilla groups.

The government’s credibility was weakened, however, during the 1982 Falklands War with Britain in which more than 600 Argentine soldiers died.

In December 1983, Bignone handed over power to democratically elected Raul Alfonsin.

Particularly since the early 2000s, Argentina has held a series of trials for human rights abuse related to the dictatorship. Last year 29 people were given life sentences for crimes at the ESMA Naval Mechanics School, which was converted into a clandestine prison and torture chamber.