EU leaders are expected to hail a breakthrough in efforts to strengthen integration in the eurozone.
However, decisions at the EU summit in Brussels to set out a range of checks and balances on eurozone banks also raise new questions about a two tier Europe.
British banks will not to subject to the new centralised scrutiny, continuing to be supervised by national authorities.
Most of the other nine non-eurozone states are considering whether to submit their banks to the new economic crackdown.
Only the UK and Denmark are able to formally opt out of joining the euro.