* Talks were frozen after Swiss vote on immigration
* Ukraine crisis has sharpened focus on supply security
ZURICH/BRUSSELS Aug 7 (Reuters) - Swiss authorities said they had resumed talks with EU regulators on a cross-border energy market, which would help to improve security of the region's energy supply.
Talks on incorporating Switzerland into EU plans for a single energy market were frozen early this year following a Swiss referendum vote to curtail immigration.
The Swiss Federal Department of Energy confirmed on Thursday that talks had resumed.
"The negotiations have been taken up again and are still ongoing, i.e. the agreement has not yet been finalised," a spokesman said, declining to give further details.
The European Commission has been seeking closer connections with Switzerland and other EU neighbours as part of efforts to create a common energy market, with improved infrastructure and technical agreements on how electricity can be traded from one country to another.
The talks were held up after the European Union criticised Switzerland over its introduction of immigration quotas, but a meeting of EU ministers in May agreed that talks could take place on bilateral relations with Switzerland covering a range of sectors.
An EU official, who asked not to be named, said this meant that the Commission, the EU executive, could hold talks on an energy deal with Switzerland.
"The European Commission will now together with the Swiss authorities look for an appropriate way how to proceed," the official said in an emailed comment.
Swiss participation is important for countries such as Italy, which border Switzerland, and Switzerland's hydroelectric capacity has value to the region as a store of power for release when demand rises.
Prior to the suspension of technical talks after the Swiss referendum in February, EU Energy Commissioner Guenther Oettinger had said the Commission was in intense negotiations with Switzerland to integrate it into the bloc's single energy market.
The EU goal of a single energy market has gained impetus because of the conflict with Russia, the bloc's biggest energy supplier, over its role in the Ukraine crisis. (Reporting by Caroline Copley in Zurich, Barbara Lewis in Brussels and Geert de Clercq in Paris; editing by Jane Baird)