EU countries that want to bail out struggling banks will continue to have leeway to do so, the official in charge of enforcing antitrust rules said on Thursday, promising to keep rules flexible into next year.

Competition Commissioner Joaquin Almunia said he intended to keep softer rules in place on state aid for banks beyond the start of next year, when the stricter regime was due to return, because of difficulties in financial markets.

The decision lowers a hurdle from EU regulators for governments that want to inject fresh capital into banks amid ever-louder calls on states to do so to avoid a fresh freeze in credit.

In late 2008, as the financial crisis gathered pace, the European Commission allowed governments to rescue lenders in return for selling off bank assets and sharing the burden with shareholders and bondholders.

It had wanted to tighten the rules again at the start of next year to wean the financial sector off state support.

"We have been preparing a specific framework dedicated to the financial sector: the new guidelines for the rescuing and restructuring of financial institutions in difficulty," the EU's antitrust chief told a conference.

"Until the summer, my intention was to introduce the new regime at the beginning of next year, assuming that the markets would have normalised by then," said Almunia.

"However, considering current market conditions, it would not be safe to introduce the new rules too soon. The situation we have been facing over the last few weeks calls for an extension of the existing state aid crisis regime for financial institutions beyond 2011. This is what I will propose."

EU documents obtained by Reuters showed top finance officials urging ministers to reinforce banks' capital while saying a systemic crisis in sovereign debt was hurting banks and risking a new credit crunch.

Concerns about exchange monopoly 

Almunia said the Commission was keeping a close eye on financial markets and their infrastructure, in particular on the power of a combined Deutsche Boerse and NYSE Euronext.

"In this particular case, we are concerned that a very large player may monopolise the derivatives markets in Europe," Almunia said.

"Therefore, any outcome that would eliminate the possibility of new entry and user flexibility would be unacceptable to us."

The combination of Europe's main futures venues Eurex and Liffe faces a tough antitrust review at the Commission because it gives the combined company a virtual stranglehold on exchange-based futures trading and clearing in Europe, known as a "vertical" market.

The deal, worth $9 billion, was the largest in a global wave of planned deals among bourses this year -- most of which failed -- and it puts pressure on Nasdaq and others.

On Wednesday, Robert Greifeld, head of Nasdaq OMX Group  stepped up opposition to the deal, saying Deutsche Boerse's acquisition of NYSE Euronext could be unfair because it would create a silo in which a single exchange would dominate all stages of the trading and clearing process.

Greifeld dropped a counter offer for NYSE Euronext earlier this year when the US government threatened to block it. – Reuters