The prime minister has held a top-level meeting with officials and ministers to discuss Britain's position in the eurozone crisis.
Downing Street confirmed Financial Services Authority (FSA) chairman Lord Turner and Bank of England governor Sir Mervyn King joined chancellor George Osborne, deputy prime minister Nick Clegg and chief secretary Danny Alexander for the discussion.
A spokesman declined to discuss the content of the meeting.
But it is known that both the Treasury and the Bank of England are preparing contingency plans to protect the UK against any fallout from the possibility of Greek exit from the eurozone and the danger that this might trigger crises in other vulnerable states like Spain, Portugal and Italy.
A Downing Street spokesman said: "The FSA chairman Lord Turner and Bank of England governor Sir Mervyn King came in this afternoon for a long planned meeting, as part of a series of meetings throughout government to ensure the UK is properly placed to deal with the eurozone situation and the issues arising from it.
"The meeting lasted an hour, and was also attended by the chancellor, deputy prime minister and chief secretary to the Treasury."
Mr Cameron has been increasingly vocal in recent weeks about the need for the 17-nation eurozone bloc to "stand behind" the single currency or face its potential break-up.
Mr Clegg said last week that "nobody rational" could desire Greek exit from the single currency, which he warned could spark a chain reaction leading to "grinding slowdown in economic activity" across Europe, including in the UK.
Downing Street said further details of the meeting were likely to be released after it has concluded.
Presenting the Bank of England's quarterly inflation report earlier this month, Sir Mervyn confirmed he and his colleagues were working on contingency plans in the event of a worst-case scenario for the euro.
Sir Mervyn said plans were being drawn up by the Bank, the Treasury and Financial Services Authority in the event of a major financial catastrophe, such as the break-up of the eurozone.