LARNACA, Cyprus — A Cyprus criminal court on Tuesday found a former defense minister guilty of manslaughter for the 2011 explosion of confiscated Iranian munitions that killed 13 people and badly damaged the country's main power station.

The three-judge panel ruled that Costas Papacostas, 73, was responsible for the safeguarding of some 80 gunpowder-filled containers and was aware of the dangers posed by the munitions, but failed to take action to prevent the detonation.

A public inquiry into the causes of the blast found that the gunpowder had spontaneously combusted after becoming unstable from prolonged exposure to wide temperature swings. The containers had been left piled on top of one another in an open field inside a naval base for more than two years.

The gunpowder was seized in February 2009 from a Cypriot-flagged ship suspected of transporting them from Iran to Palestinian militants in Gaza through Syria in breach of a United Nations ban on Iranian arms exports.

The court said that nothing was done to eliminate the danger of a possible explosion, even after some of the gunpowder detonated in one container a week before the larger, fatal blast — something that a military official had warned at the time was like a heart attack foreshadowing worse things to come.

"The danger and the warnings were such that the fact that no measure was ever taken while it was possible indicates such indifference as to constitute willful negligence," the judges said.

Papacostas was taken to Nicosia General Hospital after feeling strong chest pains shortly after entering Cyprus' central prisons complex where he is to remain until his sentencing later this month. Health Minister Petros Petrides told state-run Cyprus News Agency that Papacostas is being treated and will remain in the hospital as long as doctors deem necessary. Surgeon Gabriel Kaoutzanis who operated on Papacostas several years ago for a swollen blood vessel in his back told reporters the patient suffers from many ailments, including kidney problems.

Three top fire service officials — Fire Chief Andreas Nicolaou, his suspended deputy Charalambos Charalambous and Disaster Response Unit chief Andreas Loizides — were found guilty of the lesser charge of causing death through a reckless and dangerous act.

The court said the three had "failed to deal with the dangerous situation as they ought to have done."

Two other defendants, former Foreign Minister Markos Kyprianou and ex-deputy National Guard Chief Savvas Argyrou, were acquitted of all charges.

The court said Kyprianou was not responsible for what would happen to containers or their storage conditions, but he was following policy forged by then-President Dimitris Christofias who was weary of upsetting either Syria or Iran.

Christofias had told Syrian President Bashar Assad six months after the munitions' seizure that they would remain on the island until their return to either Syria or Iran. Testifying before the public inquiry, Christofias attributed the remark to "diplomacy."

Christofias rejected the inquiry's conclusion that he was primarily responsible for the circumstances that led to the explosion, saying his subordinates had failed to inform him about the gunpowder's storage conditions and the risks associated with its prolonged exposure to the elements.

Both Papacostas and Kyprianou resigned a few days after the explosion.

The blast triggered a political crisis on the island amid weeks of street protests calling for Christofias to quit over what many saw as the official ineptitude and the government's botched handling of the island's worst peacetime military disaster.

Some relatives of the 13 dead said Christofias should also have been tried.

Damage to the main power station — just 200 meters (yards) away from where the munitions were piled — was so severe that it caused rolling island-wide blackouts for months and cost hundreds of millions of euros (dollars) to an already faltering economy.

Manslaughter carries a maximum sentence of life in prison, while the lesser charge calls for four years in prison, a fine of around 4,300 euros ($5,500) or both.

Sentencing proceedings will start on July 24.