Princess Diana
Princess Diana said to have been filmed by Chinese tourists in a Glasgow church (Reuters)

Paranormal expert Michael Cohen is investigating video footage shot by Chinese tourists at a church in Glasgow who claim they have filmed the ghost of Princess Diana.

The tourists contacted Cohen to show him the footage of what seems to show a figure who looks like Princess Diana. She "appears" in one of the stained glass windows of the church.

Cohen claimed the footage could be hard evidence of a paranormal encounter.

"Scientists tell us that ghosts don't exist, and yet people around the world keep seeing them," he said.

"While we might want nothing to do with the dead, perhaps some ghosts have unfinished business with us."

Cohen admitted that the image could well be an optical illusion but he and a team of researchers are working to establish its authenticity.

"The footage is being examine to ascertain if it is a genuine ghost-capture," he said. "It might be a bizarre optical illusion but then again, it could be a ghost - possibly Princess Diana's.

"Ghosts often appear in places connected to their lives and families. Ghosts might appear to warn individuals, groups and even entire nations of possible impending danger."

Princess Diana died in a car crash in Paris in 1997, which triggered multiple conspiracy theories. A French investigation concluded the death was because of the driver's drunken loss of control.