European shares fell and the euro eased to a 3-week low on Thursday as a delay in a decision on a crucial bailout for Greece unnerved investors and prompted a pause in the market rally that has marked the start of 2012.

A three-hour teleconference between euro zone finance ministers late on Wednesday failed to resolve all the issues surrounding a second aid package for Athens, putting off any decision on the matter until February 20 at the earliest.

There are no answers on how Greece will be treated ... If there is no resolution it poses risks for the euro, said Carl Hammer, chief currency strategist at SEB in Stockholm.

There is a risk that the possibility is opened up for a break-up of the euro zone, that if one falls out others will follow. In response the euro slid 0.4 percent to $1.3010 to be near its January 25th low just under $1.30.

The FTSEurofirst index of top European companies <.FTEU3> opened down 0.5 percent at 1,070.58.32 points. After falls in Asia, the MSCI world equity index <.MIWD00000PUS> was down 0.6 percent.

Several sources also told Reuters euro zone finance officials are now examining ways of delaying part or even all of the second bailout program, even if a deal is agreed on Monday, while still avoiding a disorderly default.

Debt markets reflected the nervousness over the Greek deal delay with German government bond prices edging higher, but the focus is on new supply with Spain expecting healthy demand at its sale of up to 4 billion euros of 2015 and 2019 bonds. France and the Netherlands are also due to offer new debt.

(Additional reporting by Jessica Mortimer; editing by Patrick Graham)