OSLO, June 10 (Reuters) - Norway will return the NH90 military helicopters it ordered from France's NH Industries because they are either unreliable or were delivered late, the defence minister and the head of the military said on Friday.

The government said it would also seek repayment of 5 billion crowns ($523 million) plus interest and other costs from NH Industries, which is owned by Airbus Helicopters (AIR.PA), Italy's Leonardo (LDOF.MI) and Fokker Aerostructuresof the Netherlands.

NH Industries was not immediately available for comment.

"No matter how many hours our technicians work, and how many parts we order, it will never make the NH90 capable of meeting the requirements of the Norwegian Armed Forces," Defence Minister Bjoern Arild Gram told a news conference.

The original contract for 14 helicopters was signed in 2001 but Norway has received only eight, the ministry said.

"We have a helicopter that doesn't work the way it's supposed to," said General Eirik Kristoffersen, the head of Norway's armed forces.