The chair of Europe's top securities regulator has written to the European Commission to demand greater flexibility over the timeframes it is being set for drafting legislation, heightening concerns over the ability of the watchdog to meet its deadlines on crucial post-crisis rules.

Steven Maijoor, the chairman of the European Securities and Markets Authority, revealed during an October meeting with one of the agency's stakeholder groups that he had contacted the European Parliament over the nature of the deadlines being set.