Flying Toblerones, mysterious illnesses and silky-white substances are among hundreds of close encounters described in previously top-secret files released by the Ministry of Defence (MoD) on Wednesday.

More than 6,000 pages of material spanning from 1994 to 2000 holds hundreds of other-worldly experiences with unidentified flying objects (UFOs) and apparent aliens across Britain.

They include reports of hundreds of alleged sightings over Bonnybridge, near Falkirk - as well as a report by a senior air traffic controller at Prestwick Airport, near Ayr.

Aircraft of all shapes and sizes have been witnessed flying over a wide range of locations - including Chelsea Football Club and the former Home Secretary Michael Howard's home in Kent.

This fifth instalment of documents released under a three-year project between the MoD and The National Archives consists of 24 files of sightings, letters and Parliamentary Questions.

They include a request submitted to former Prime Minister John Major from a councillor for an inquiry into 600 alleged sightings in Bonnybridge, Scotland, known as the "Bonnybridge Triangle".

View STV's shock video footage of a UFO hovering over Bonnybridge

Video: UFO expert Dr David Clarke ponders the supernatural

In October 1997, Councillor William Buchanan, of Falkirk District Council, who supported the claim of 600 sightings in two years, wrote to Mr Blair demanding the phenomena were investigated after five years of pursuing the matter.

He wrote: "For five years the people both you and I represent have witnessed a phenomenon in the area that has been left unexplained. UFOs over 3,000 people have witnessed, some have photographed, some have videoed, then lights and objects.

"I wrote to your predecessor John Major, I have also contacted our local MP Dennis Canavan who put me in contact with the MoD who told me quite strongly that nothing was happening in Bonnybridge that was a threat to national security."

He went on: "I have tried to get an answer for the people and have been ridiculed for it. I appeal to you Mr Blair to get the phenomenon investigated."

But an MoD response to the letter said there were no grounds to investigate the matter. However, Mr Buchanan did not give up and wrote to Mr Blair once again in 1998 demanding "the truth".

The documents also detail an object travelling at more than 1,000 knots was tracked by a senior air traffic controller from the control tower at Glasgow Prestwick Airport, in Ayrshire, in February 1999.

Meanwhile, another report states that a West Lothian electrician spotted a "Toblerone-shaped" UFO hovering over a field. A sketch of the craft is included in the report.

Experts believe the records highlight how shapes of reported UFOs have changed over the last half-century. This could be explained by representations of UFOs in popular culture - such as TV shows like The X-Files.

Many reports in this latest file describe aircraft as big, black and triangular in shape with lights along the edges, whereas the predominant form in the 1940s to 1950s was saucer or disc-shaped.

The files are available to download for free for a month from the website www.nationalarchives.gov.uk/ufos