Two former Cypriot ministers and four other senior officials pleaded not guilty on Monday to charges of manslaughter and negligence relating to a deadly munitions explosion that was the island's worst peace-time disaster.
A stock of confiscated Iranian munitions exploded in July last year, killing 13 people and destroying Cyprus's largest power station.
The resulting power outage and repair costs hit economic output on the island which was forced to seek a financial lifeline from its EU partners last month.
Former foreign minister Marcos Kyprianou and ex defence minister Costas Papacostas were put on trial alongside the ex head of fire brigade, the deputy head of fire brigade, the former deputy commander of the army and the former head of the emergencies services department.
All six pleaded not guilty to all charges against them, the semi-official Cyprus News Agency reported.
The munitions were discovered on a vessel sailing from Iran to Syria in 2009, and seized by Cypriot authorities because the shipment violated U.N. sanctions.
They were offloaded and stacked in sweltering temperatures for more than two years in a military compound adjoining Vassilikos, the island's largest power facility.
It was subsequently disclosed that army officials had repeatedly warned of unsuitable storage conditions.
Kyprianou, a former EU commissioner, and Papacostas resigned from their ministerial posts after the blast.
An independent state-appointed investigator last year said the island's government had ignored security concerns about storing the cargo on the island instead of disposing of it because it did not want to upset Syria.
The court adjourned until August 27, with further court hearings arranged for September, the news agency said.