By Michele Kambas

NICOSIA (Reuters) - An independent investigator accused Cypriot President Demetris Christofias on Monday of direct personal responsibility for a munitions blast that destroyed the island's main power station and hammered its economy.

In particular, investigator Polys Polyviou accused him of ignoring safety considerations to avoid upsetting nearby Syria, the intended destination of the confiscated stockpile of Iranian munitions.

Thirteen people died when the munitions blew up on July 11 after being stored at a navy base in the south of Cyprus, often exposed to scorching heat, for over two years.

Authorities repeatedly ignored warnings from army officers about deteriorating storage conditions, according to the state-appointed inquiry headed by Polyviou, a respected barrister.

He said Christofias had known about the danger of the munitions but failed to act, and shared the blame with two ministers who have already resigned. The president, who has immunity from prosecution, has denied responsibility.

The munitions were confiscated from a Cyprus-flagged vessel heading to Syria from Iran in early 2009 for violating U.N. weapons sanctions, and were kept in Cyprus, but not destroyed.

The inquiry heard that Christofias assured Syrian President Bashar al-Assad that the cargo would remain in Cyprus until it could be returned to either Syria or Iran.

"Knowing the dangers of the cargo, the president did not take any action for its safekeeping," said Polyviou, concluding a public inquiry that lasted two months.

"The president of the republic appeared to have adopted the policy, because of Syria, that the cargo should remain in Cyprus and not be destroyed ... The president showed gross negligence, with the result that 13 lives were lost."

The blast has also knocked back Cyprus's economic growth projection to zero this year from 1.5 percent, at a time when its banks are already under pressure from Greece's debt crisis.

Christofias told the inquiry that his ministers had kept him in the dark, and that he had not known that the cargo was stored just 150 meters (164 yards) from Cyprus's largest power station, Vassilikos, which was destroyed in the explosion.

The inquiry heard that Cyprus had on three occasions obstructed U.N. weapons inspectors from checking the munitions store.

Christofias, a communist elected in 2008, has faced almost daily protests calling for his resignation.

Police are due to pass a report of their own criminal investigation on Tuesday to the attorney-general, who must decide whether charges should be filed and against whom.

Although Polyviou's findings are non-binding, he implied that Christofias should face criminal charges:

"I have the view, particularly where criminal offences are concerned, that the attorney-general should examine the possibility of such crimes being committed by all involved, without exception."

(Editing by Marwa Awad and Kevin Liffey)