The rift between David Cameron and eurozone leaders is set to widen following comments from the prime minister criticising the European Union for pushing for closer integration – a move he believes could compromise the block’s free market rules.
Speaking in Perth, Australia, where the prime minister is attending the Commonwealth summit, he said: "London is the centre of financial services in Europe. It's under constant attack through Brussels directives. It's an area of concern, it's a key national interest that we need to defend."
"As the 27 we need to make sure that the single market is adequately looked after," he added.
"There are a lot of things the eurozone is doing together. Having more meetings alone, establishing machinery - it raises the question of could there be caucasing?"
Cameron said that It was important that the institutions of the 27 are properly looked after and that the Commission does its job "as the guardian of the 27".
On Thursday, Chancellor George Osborne attempted to placate the increasingly vocal band of eurosceptics within his own party by promising that UK money would not be earmarked to bail out the struggling single currency.
The deal, struck on Thursday morning, detailed a package to write-off 50% of Greek debt holdings. The European Financial Stability Facility (EFSF) is to be leveraged to 1 trillion euro (£880 billion). Billions will also be pumped into vulnerable banks to protect them from failure.
The measures did not go as far as many financial experts had been demanding over recent months. But updating MPs on the developments, Osborne said the eurozone now appeared to be on the "right road".
"Our view is that last night very good progress has been made towards solving the immediate crisis, very good progress on all fronts," he said.
"But much detail remains unresolved and having put pressure on the eurozone to get this far, we have to keep up the pressure to get the details completed. They have started down the right road and now they have to finish the job."
He insisted that Britain will not contribute money to the EFSF bailout fund - but did concede that extra money could go to the IMF.
"Supporting countries that cannot support themselves is what the IMF exists to do and there may well be a case for further increasing the resources of the IMF to keep pace with the size of the global economy," he said.
"Britain, as a founding and permanent member of its governing board, stands ready to consider the case for further resources and contribute with other countries if necessary."
But he stressed: "We are only prepared to see an increase in the resources that the IMF makes available to all countries of the world. We would not be prepared to see IMF resources reserved only for use by the eurozone."
Elsewhere, French President Nicolas Sarkozy has admitted that it had been an “error” to let Greece join the eurozone.
"It was an error because Greece entered with false figures… it was not ready,” Sarkozy told French TV.
"We had to face up to all this. If the euro had exploded on Wednesday night, all of Europe would have exploded. If Greece had defaulted there would have been a domino effect carrying everyone away.”