Six people have been arrested on suspicion of a plot to disrupt the London Stock Exchange.
The Met Police said information suggested activists from the Palestine Action group were intending to target the exchange on Monday.
The force said it was believed those involved were planning to cause damage and “lock on” in an effort to stop the building opening for trading.
Arrests were made in London, Liverpool and Brighton on Sunday.All six people are currently in custody.
The Met said it was “mindful of the suggestion that this was one part of a planned week of action”.
It said it was in contact with other forces, including City of London Police, to ensure any further disruption could be dealt with.
The Met said the arrests were prompted by information shared by the Daily Express.
Det Supt Sian Thomas said: “These are significant arrests. We believe this group was ready to carry out a disruptive and damaging stunt which could have had serious implications had it been carried out successfully.
“A 31-year-old man from Liverpool was arrested on suspicion of conspiracy to cause criminal damage by officers from Merseyside Police in the early hours of Sunday.
Five others were arrested over the same offence later in the day, including a woman, 29 from Brent in north London, a 23-year-old man from Tower Hamlets in east London, two women, aged 28 and 26, from Liverpool and a 27-year-old man in Brighton.
“I’m grateful to the Express for their willingness to provide the information gleaned from their own investigation,” Det Supt Thomas said.
“It was instrumental in helping us intervene successfully. Having only been provided with the material on Friday afternoon we had limited time to act.
“She said it was thanks to the “determined efforts” of the Met’s public order crime team and colleagues in Merseyside that officers “were able to identify, locate and arrest those we suspect to be involved in this plot”.
