Anti-capitalism protesters from the Occupy movement have begun a new protest in the City of London as part of a global day of action.
Other protests are underway in cities including Moscow, New York, Athens and Madrid.
Several hundred people have gathered outside St Paul's Cathedral for a rally, before moving on to demonstrate outside the offices of some of the largest firms in the financial heart of London.
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In a wide-ranging Peston on Sunday interview, he said Parliament security needs reviewing and the PM's counter-terror strategy is flawed.
The terror attack carried out by Khalid Masood at Westminster that left four people dead lasted less than two minutes say police.
Two knives were found at the scene in Islington, North London, and the suspects fled on foot before being arrested.