BUCHAREST, Sept 9 (Reuters) - A Romanian Navy dredger hit a drifting mine it was trying to defuse in bad weather on Thursday, but the crew of 75 were unharmed by the explosion, the defence ministry said.

Mines began floating in the Black Sea after Russia invaded Ukraine on Feb. 24, and Romanian, Bulgarian and Turkish military diving teams have been defusing those drifting in their waters.

The ministry said the ship was alerted about a mine drifting about 25 nautical miles northeast from the Romanian Black Sea port of Constanta, but couldn't defuse before being hit by it because of high winds and waves.

"There are no victims or injured following the explosion, the 75 troops on the ship are not in danger, the ship's floatability is not affected and there is no major damage on board," the ministry said in a statement.

The Black Sea is crucial for shipment of grain, oil and oil products. Its waters are shared by Bulgaria, Romania, Georgia and Turkey, as well as Ukraine and Russia.

Since the war started, Turkey, Romania, Bulgaria and Ukraine have destroyed 28 mines in western waters of the Black Sea, the ministry said.