A Scotland Yard spokesman said officers arrived at the camp in Leyton Marsh at 8am "in support of bailiffs acting on behalf of the Olympic Delivery Authority and Lee Valley Park Authority to enforce an eviction and possession order".
"Police are dealing with a group of up to 30 people who are blocking access to the ODA site, and refusing to move."
"Officers at the location have warned those people present that Section 14 of the Public Order Act has been applied to them and sets the condition that the protest must move within a short period of time to allow access to the site."
Four people have been arrested for public order offences.
G4S should be the first outfit on a Government blacklist of high-risk firms that have failed to deliver, MPs have said.
Transport for London has created a new version of the tube map, to celebrate the success of Team GB at the London Olympics.
Olympic hero Mo Farah has shown off the newborn twins who inspired him to double gold-winning victory - and finally revealed their names.