Thousands have taken to streets of London to protest Iraq and Afghanistan wars and ask gov't for troops' return, leading to four arrests.

Thousands of protesters marched from Trafalgar Square to parliament to call for the government to withdraw troops from Iraq as politicians gathered on the first day after the summer recess on Monday. Permission to hold the event was given less than an hour before the start, organizers said.

"I feel it is important to show solidarity with a growing realization that the war was wrong," said George Solomou, who refused his call up to serve in the conflict.

Although protesters earlier assured the police that they had no intention to disrupt parliament or block the way of the MPs, some of them sat down in the road in Parliament Square. Police arrested four people during the protest.

Police claims the four were detained for offenses including assault on police officers and obstruction.