Cyprus ex-defence minister Costas Papacostas was on Tuesday found guilty of manslaughter while three fire chiefs were convicted of causing death through negligence linked to a munitions dump blast in 2011 which killed 13 people.

Papacostas was also found guilty of causing death through negligence, but the more serious charge of manslaughter carries a maximum sentence of life in prison.

Ex-foreign minister Marcos Kyprianou and army deputy commander Savvas Argyrou were found not guilty on all charges by the criminal court in the southern city of Larnaca.

Relatives of those killed and injured in the blast on July 11, 2011 at the island's Mari naval base on the south coast were angry at the verdicts.

They claimed all the defendants "and many more" should go to prison for life. They called the verdicts an "injustice".

The fire chiefs face up to four years in prison each.

They and Papacostas will reappear in court for sentencing on July 24 and arguments for leniency. The fire chiefs were also found guilty of reckless or dangerous behaviour.

It is said to be the first time in the island's legal history that so many senior officials have faced such serious charges.

Burning containers with 400 tonnes of gunpowder triggered an estimated 1.5 megaton blast that damaged 730 homes and businesses.

There was a public outcry after munitions stored at the naval base for almost three years, under searing heat in summer, exploded despite repeated warnings that they were unsafe.

Some 98 containers were piled up unprotected at the base, just 150 metres (yards) from the island's biggest power station at Vassiliko.

They were seized in February 2009 when Cyprus intercepted a Cypriot-flagged freighter bound from Iran for Syria and a UN sanctions committee said the cargo contravened a ban on Iranian arms shipments.