LONDON: Britain could restrict the immigration of Greeks and other citizens of euro zone  countries affected by Europe's sovereign debt crisis in the event of "extraordinary stresses and strains", Prime Minister David Cameron said on Tuesday.

"The legal position is that if there are extraordinary stresses and strains it is possible to take action to restrict migratory flows, but obviously we hope that doesn't happen," he told a parliamentary committee.

"I would be prepared to do whatever it takes to keep our country safe, to keep our banking system strong, to keep our economy robust," he added.

European Union rules allow the free flow of people to live and work around the group's 27 member states, but fears have mounted in Britain of a wave of migrants from struggling states such as Greece and Spain if their economies continue to worsen.

Cameron said greater European banking integration - a likely response by the euro zone's 17 member states to the crisis - would not necessarily mean big changes for Britain if the right safeguards were in place.

Some in Britain worry that a powerful euro zone banking bloc could change financial rules that impact London, Europe's biggest financial center and on which Britain relies for a large chunk of its revenues.

Cameron wants safeguards that a euro zone banking union would not use its clout to bounce Britain into decisions it does not agree with.

"If the 17 countries of the euro zone bring about a banking union for themselves, which I think frankly they need to do .... and if we can get proper safeguards in place then that wouldn't be a fundamental change for us," Cameron said. AGENCIES