Armed soldiers wearing plain clothes will be on undercover patrol at some of the UK's biggest Bank Holiday events over fears of a terrorist attack, according to reports.

Although there is no specific intelligence, the UK's terror threats level remains of "severe" – meaning an attack is likely – following the attacks in Westminster, Manchester and Finsbury Park.

Authorities are also on high alert in the wake of the double terror attacks in Spain, which left at least 14 people dead.

Extra steps are now been taken to ensure the safety of those attending events in the upcoming bank holiday weekend, such as Manchester Pride, the Reading and Leeds music festivals and the Notting Hill Carnival.

According to reports, armed guards will mingle with the public at certain events and be called upon if needed. One unnamed source, who had seen a security report, told the Mail on Sunday: "They will be casually dressed with their weapons hidden beneath their clothes. They won't be in traditional military vehicles, either.

"Recently a company of Special Forces Support Group troops completed a live firing exercise using civilian armoured vehicles and they will be called upon. . . the other troops who have been called up for the bank holiday weekend include personnel from the Special Reconnaissance Regiment."

Met Police has not yet confirmed how they will operate at this year's Notting Hill carnival, which is expected to see around two million people in attendance.

The reports arrived as this year's Edinburgh Festival installed barriers to prevent a vehicle attack similar to that seen in terror attacks across Europe, including Westminster, London Bridge and Barcelona.

An Edinburgh Festival Fringe Society spokesperson said: "This year, and as with other major cities and events, a range of additional security measures have been installed in various locations across Edinburgh. Our priority and the priority of all the agencies and organisations involved in the Fringe is the safety and security of audiences, participants and staff."

Similar barriers have already been installed at Westminster Bridge in order to prevent a repeat of March's attack, in which six people were killed.

Notting Hill Carnival 2016
More than two million people are expected to attend Notting Hill CarnivalDaniel Leal-Olivas/AFP