A serious organised crime gang facing jail after being snared by police is the "most sophisticated" group of its kind encountered by the Scottish force, a court has heard.

The High Court in Glasgow heard how the group's operation centred around the importation of huge quantities of class A drugs, acting as wholesalers to other dealers.

Prosecutors told how the group was at the "top of the chain" for drugs transactions in Scotland and the UK and had access to an "unprecedented" level of firepower.

Nine men, including Martyn Fitzsimmons, previously of Bulldale Street, Yoker, pleaded guilty on an earlier occasion to charges involving serious criminal activity, including firearms, drug dealing and violence.

Amid high security, 37-year-old Fitzsimmons and the others returned to the court on Monday to hear the Crown reveal extensive details of their criminal activities, which span the period from 2013 to this year.

The men, who are all remanded in custody, will be sentenced next month.

Advocate depute Alex Prentice QC told the court that the case marks the culmination of four separate major police investigations into serious and organised crime - Operations Drakken, Escalade, Pembridge and Textural.

He said: "The organised crime group (OCG) is the most sophisticated group encountered by Police Scotland.

"Their operation centres on the importation of vast quantities of cocaine. Their role is as wholesalers to other organised crime groups.

"They are at the top of the chain in terms of drugs transactions in Scotland and the United Kingdom as a whole."

He told how the gang would package and hide substantial amounts of cash for taking to senior group members and were involved in the trafficking of firearms to enforce their operations.

"The firepower at the disposal of this crime group is unprecedented in terms of the history of organised crime in Scotland," added Mr Prentice.

The nine men in the dock were David Sell, 50, Barry O'Neil, 37, Anthony Woods, 44, Francis Mulligan, 41, Michael Bowman, 30, Mark Richardson, 30, Gerard Docherty, 42, Steven McArdle, 33, and former soldier Fitzsimmons.

The court heard how Richardson has two previous High Court convictions for drugs offences, while Fitzsimmons was previously jailed for 12 years in England for procuring explosives, weapons and ammunition.

The court heard how the gang would use vehicles and a network of industrial premises let under false names and addresses.

Police searches of those locations led to the seizure of more than 1,000 items, the Crown said.

These included encrypted mobile phones, multiple disposable mobile phones, laptops, tablets, counter-surveillance equipment, firearms - including automatic pistols, machine guns and a grenade - and around £1.6 million in cash.

Mr Prentice told how "violent means" were deployed by the gang and it became clear that they were connected to the abduction and assault of drug dealer, as well as a shooting in Edinburgh.

Sell admitted being involved in the abduction, although his lawyer stressed his limited involvement in the incident. Other unidentified men were also said to have been involved.

The court heard how the man agreed to a drug deal but later found himself in debt to the group and fled to England.

There, he was traced to his home, seriously assaulted, bound in chains and bundled into a van and driven back to Scotland.

The court heard he then suffered further potentially life-threatening violence, including being punched, kicked, whipped with a chain, hit with a sledgehammer, sprayed with bleach and shot three times in the knees.

He was found by members of the public after being pushed down a hill.

Mr Prentice told how police under took a major surveillance operation in relation to the gang, running from June 2016 to January 2017.

It was during that operation that Docherty was found to have fired shots at a home in the Ratho area of Edinburgh, the court was told.

Other items recovered by officers included number of high-powered stolen cars and they found "sophisticated" concealment areas in cars and industrial premises.

A stash of carefully-wrapped firearms - including Glock and Beretta pistols - was found in an "engineered compartment" in the rear bumper of a Honda car in February, the court was told.

One expert concluded that "the amount of cash and firearms recovered in this case was indicative of an international operation," Mr Prentice said.

Judge Lord Beckett deferred sentence to January 22 to allow for the preparation of background reports.

Pleas in mitigation for the nine accused are expected to be heard at that stage.

Fitzsimmons was jailed for 12 years in 2008 after being convicted of stealing a large stash of arms and selling them to murdered gangster Kevin "Gerbil" Carroll.

He had served with the Argyll & Sutherland Highlanders and then para-regiment between 1996 and 2008, reaching the level of lance corporal. He had tours in Northern Ireland, Bosnia, Iraq and Afghanistan, including on covert SAS missions.

He had a string of convictions, while serving, for violence and disorder while he was on leave and drinking.

But in 2008, along with two others, he stole high-powered guns, ammo, detonators, flares and smoke grenades from British Army barracks in Canterbury, Kent.

Last year at Dumbarton Sheriff Court, he pleaded guilty to sending threatening letters to a relative and a former friend from his youth.

Because the crimes were commited before he was released on parole, he couldn't be sent back to prison. Sheriff Simon Pender restricted him to a property in Whitehill Court, Dennistoun, in the evenings for six months. He was ordered to complete the maximum 300 hours of unpaid work.