"A vehicle was stopped and a man in his early 30s arrested on suspicion of a public order offence. The vehicle he was driving, a white Ford Transit, was deemed suspicious," the spokesman was quoted as saying by the Sky News broadcaster.
The police spokesman told Sputnik later on Monday that the law enforcement had not found anything suspicious about the van.
The cordon has been lifted in the area, and traffic has begun moving again.
Security measures in London have been tightened after a series of deadly terror acts which hit the UK capital in 2017, including ramming attacks near the Westminster Palace in March, at London Bridge in June, and at the Finsbury Park also in June.