Arrests of Occupy London demonstrators were made by City of London police at a protest outside the Bank of England on Saturday, but representatives of the two sides gave BBC News conflicting reports on the number of them.
The Occupy London reps said as many as 40 people were arrested, while the police reps said 11 of them were detained.
The arrests were made for public-order offenses, BBC News quoted police as saying.
The London demonstration with about 300 protesters was one of a number of actions in more than 50 countries on Saturday, according to the Occupy Wall Street online site.
First flowering in New York last September, the Occupy protest movement's roots are in the continuing global financial crisis that became apparent in late 2007.