Ministers are continuing to "take steps" to shield Britain from the impact of economic turbulence in the eurozone amid fears Greece is on the brink of crashing out of the single currency after its pleas for a bailout extension were rejected.
Chancellor George Osborne was briefed as eurozone finance ministers meeting in Brussels refused to extend the financial assistance package in place to help the failing economy.
It will end as planned on Tuesday - the day Greece must make a debt repayment of 1.6 billion euro (£1.1 billion) to the International Monetary Fund that it cannot afford.
Eurozone ministers criticised Greek prime minister Alexis Tsipras for announcing that a snap referendum on bailout proposals will be staged next week.
The left-wing Syriza leader said proposals put forward by international creditors would place "unbearable" burdens on the Greek people and the government will now campaign for a "No" vote.
A Treasury spokesman said: "We urge the people of Greece to resolve the current uncertainty, and ensure economic and financial stability across Europe.
"We have taken measures to increase our economic security so we can deal with risks like this from abroad, and we continue to take steps to prepare and protect ourselves from all eventualities”.
Finance ministers in the bloc said creditors had put forward a "comprehensive" proposal to break the deadlock.
In a statement, the Eurogroup said: "Regrettably, despite efforts at all levels and full support of the Eurogroup, this proposal has been rejected by the Greek authorities who broke off the programme negotiations late on the 26 June unilaterally.
"The Eurogroup recalls the significant financial transfers and support provided to Greece over the last years. The Eurogroup has been open until the very last moment to further support the Greek people through a continued growth-oriented programme.
"The Eurogroup takes note of the decision of the Greek government to put forward a proposal to call for a referendum, which is expected to take place on Sunday July 5, which is after the expiration of the programme period."
If Greece fails to meet its debt repayment it will be declared in default, pushing it towards the exit door of the single currency.
Greek finance minister Yanis Varoufakis said his government was still "fighting for there to be a last-minute deal by Tuesday".