The green Cherokee had the registration L808 RDT, Strathclyde Police said.

Assistant chief constable John Malcolm said he wanted information about sightings of the 4x4 over the last days and weeks.

Mr Malcolm was joined at a press conference in Glasgow by Scotland Yard's anti-terror chief, Deputy Assistant Commissioner Peter Clarke,

He revealed that a critically-ill suspect under armed guard in hospital is believed to have been the driver of the vehicle.

The second man in police custody was 27 years old.

The officer issued a public plea for the public to provide videos or photographs of the incident and its build-up.

Mr Malcolm said "Of the two men arrested yesterday afternoon, I can confirm one man remains in a critical condition within the Royal Alexandra Hospital, Paisley.

"He is under armed police guard and I believe he was the driver of the vehicle.

"The other man, 27 years old, remains in police custody."