FORENSIC officers were spotted this morning scouring surfaces at the Buchanan Street Subway station. 

Accompanied by uniformed police officers, a person in a white boiler suit was seen taking samples from the city centre building, leaving onlookers puzzled. 

Police remained tight-lipped about the probe, telling the Glasgow Times earlier today: "Officers were assisting an external agency with an annual survey."

But we can now reveal that the study was being carried out by investigators from the Department for Science and Technology Laboratories (DSTL), part of the UK Government's defence and security operations. 

It was a "routine investigation" to test the levels of traces of explosives in the environment. 

It is important to know the levels of explosives in the environment normally, explained the DSTL, because it can help with criminal investigations and interpreting evidence. 

Investigators wear distinctive white suits to stop their samples from being contaminated, the Department said. 

An information leaflet sent by the Department read: "Scientists from the DSTL are conducting a routine survey to detect and identify traces of explosives present in the general environment.

"There is no need to be concerned, these types of survey are routine and this work is not related to any specific threat or any Covid-19 concerns.

"Numerous locations and are being sampled, particularly transport, retail and leisure hubs.

"Personnel undertaking the survey are wearing protective clothing to ensure they do not contaminate the particular areas being sampled and we get a true picture of any background contamination.

"The sampling techniques used are non-invasive, non-toxic and leave no residue.

"The data is used to understand the level of explosive traces in our environment and can be used to interpret evidence gathered at potential crime scenes to aid the criminal justice system and maintain the security of the UK.