SARAJEVO, March 7 (Reuters) - European power grid lobby ENTSO-E urged Serbia and Kosovo to urgently resolve a dispute over their power grid, which has affected the broader European network, causing some digital clocks on the continent to lose time.

The grid shared by Serbia and its former province Kosovo is connected to Europe’s synchronized high voltage power network.

ENTSO-E, which represents European electricity transmission operators, said the continental network had lost 113 gigawatt-hours (GWh) of energy since mid-January because Kosovo had been using more electricity than it generates. Serbia, which is responsible for balancing Kosovo’s grid, had failed to do so, ENTSO-E said.

The loss of energy had meant that electric clocks that are steered by the frequency of the power system, rather than by a quartz crystal, to lag nearly six minutes behind, ENTSO-E said.

Many digital clocks, such as those in alarm clocks and in ovens or microwaves, use the frequency of the power grid to keep time. The problem emerges when the frequency drops over a sustained period of time.

ENTSO-E said the European network’s frequency had deviated from its standard of 50 Hertz (Hz) to 49.996 Hz since mid-January, resulting in 113 gigawatt-hours (GWh) of lost energy, although it had appeared to be returning to normal on Tuesday.

“Deviation stopped yesterday after Kosovo took some steps but it will take some time to get the system back to normal,” ENTSO-E spokeswoman Susanne Nies told Reuters. She said the risk could remain if there is no political solution to the problem.

The political dispute centres mainly on regulatory issues and a row between Serbia and Kosovo over grid operation. It is further complicated by the fact that Belgrade still does not recognise Kosovo.

“We will try to fix the technicalities by the end of this week but the question of who will compensate for this loss has to be answered,” Nies said.

ENTSO-E urged European governments and policymakers to take swift action and exert pressure on Kosovo and Serbia to resolve the issue, which is also hampering integration of the western Balkans energy market required by the European Union.

“These actions need to address the political side of this issue,” ENTSO-E said in a statement. The grid operators in Serbia and Kosovo were not immediately available to comment.

Kosovo seceded from Serbia in 2008. Both states want to join the European Union but Brussels says they must normalize relations to forge closer ties with the bloc.

Serbia and Kosovo signed an agreement on operating their power grid in 2015. However, it has not been implemented yet as they cannot agree on power distribution in Kosovo amid conflicting claims about ownership of the grid, built when they were both part of Yugoslavia. (Writing by Maja Zuvela; Editing by Susan Fenton)