Deputy Prime Minister Nick Clegg has dismissed suggestions that Britain is planning to "pull up the drawbridge" on any exodus of workers from crisis-hit eurozone nations.
His intervention came after Home Secretary Theresa May disclosed that contingency planning was under way to deal with a potential influx of would-be immigrants.
There are fears that Greece in particular could leave the euro and go bankrupt, causing millions of people to lose their jobs and possibly look for work abroad.
But Mr Clegg said she had only been talking about "keeping an eye on migration patterns".
"I really do think some of the breathless talk in the media about do we pull up the drawbridge to stop hordes of people migrating across Europe is both far-fetched, somewhat apocalyptic in tone and deeply unhelpful," he told BBC1's Andrew Marr Show.
"We are not there yet."
The Deputy Prime Minister said he hoped Greece would remain a member of the euro. Mrs May had said "quite sensibly that these are things that the Home Office keeps under review, as it should", he added.
Mrs May said in an interview with The Daily Telegraph yesterday that "work is ongoing" to deal with large movements of people in the event of the break-up of the single currency.
She did not indicate the sort of response that was under consideration.
In normal circumstances the Government's hands are tied because EU nationals are largely entitled to live and work anywhere in the single market. But she said the Government was "looking at the trends" on immigration from struggling European economies.