An X-Files UFO probe was launched when a couple marked their house-warming party by releasing floating lanterns into the night sky.

When Paul McKinney and Emma Henfrey heard the following day that police had been contacted with about 20 calls from worried residents, they swore their friends to secrecy.

It took a Ministry of Defence (MoD) investigation before they knew they had to come clean.

Paul, 28, and Emma, 30, celebrated moving into their new home in Wycliffe Road, Seaham, County Durham, by holding a party for friends.

They set the floating lanterns, bought as a gift by neighbour Quentin Carr, into the air.

But the orbs, which glow bright orange then silvery white, caused a real stir and some stargazers thought they were seeing extraterrestrial spaceships overhead.

Mr McKinney said: "It was an awesome experience to watch these lanterns float up and away and we never though for a second that people would think that they were aliens."

The lanterns party-goers set off that night are on sale on the Internet for about £10 and carry a manufacturers' warning that they have been mistaken for UFOs.

They fly up to 1,000ft and look like hot-air balloons.

Witnesses who spotted the lanterns over the coast were convinced they were seeing UFOs.

Harry McCall, 67, and his wife, Elizabeth, of Stockton Road, Seaham, reported seeing the lights.

Mr McCall said: "I said they were UFOs until I was convinced otherwise, and now I have been.

"It is quite funny to find out and it's good to know an explanation.

An MoD spokeswoman said: "We examine UFO sighting reports to establish whether there is any evidence to suggest that UK airspace has been compromised by hostile or unauthorised air activity."