Parapsychologist Jason Karl, president of the Ghost Research Foundation International (GRFI), said the city has more spooks than any other.

And tourism officials in the city hope the title will help boost the number of visitors to the area.

The organisation was founded by Mr Karl nearly 10 years ago and aims to research alleged ghostly phenomena worldwide.

"We have travelled extensively working on research projects across the globe and nowhere have we found more ghosts than in York," he said.

Haunted buildings in York

Treasurer's House Theatre Royal St William's College King's Manor Holy Trinity church

The city, which has four million visitors each year, holds regular ghost walks which can attract nearly 150 tourists at a time.

One of the most famous phantom visitors in York is the Grey Lady, who is said to haunt the room behind the dress circle of the Theatre Royal.

She is regarded as a good omen to any performers who see her.

The Grey Lady was a nun who was bricked into the walls as a punishment for becoming the lover of a nobleman.

St William's College, near York Minster, is said to be haunted by a thief who died after robbing a wealthy priest.

We have always had an idea that York is the most haunted city but it's the first time it's been validated

Kay Hyde, of York Tourism Bureau

To mark its paranormal status, York will be hosting GRFI's 10th anniversary celebrations on 6 and 7 September.

Members of the public will be able to take part in real ghost investigations run by psychic investigators and scientists.

Kay Hyde, public relations manager for York Tourism Bureau, said: "It is fantastic for the city.

"We have always had an idea that York is the most haunted city but it's the first time it's been validated."

Gillian Crudas, chief executive of York Tourism Bureau, said: "We are delighted that the Ghost Research Foundation International has decided to hold it's 10th anniversary celebrations in York.

"It's fantastic that visitors and residents will be able to take part in real live investigations and we are sure it's going to create a lot of interest."