PRAGUE -(Dow Jones)- Ongoing police investigations into the electronic theft of carbon dioxide emissions permits in three European countries are preventing Czech and other European registries from reopening following an indefinite ban on spot trading of permits being enacted last week, the head of the Czech registry said Thursday.

"It's now impossible to predict a date for restoring the activity of our registry, just like with pan-European organized trade of emissions allowances," Jiri Stastny, chairman of OTE AS, the Czech state-owned emissions registry, told Dow Jones Newswires in an email response to questions.

The causes of the indefinite delay are "organizational and the ongoing police investigations" rather than technical problems within the registry itself, he said.

The registry will release a formal statement early Friday to clarify its position, Stastny said.

The registry late last week increased the total number of companies hit in the Czech cyber theft to six.

The number of allowances stolen from the Czech registry exceeds 1.3 million and has a value of EUR19.4 million, based on the market price of EUR14.93 per allowance as of 1204 GMT Thursday.

Earlier Thursday Czech power company CEZ AS (BAACEZ.PR) said 700,000 allowances disappeared from its account at the registry last week, and it is demanding the registry replace the stolen credits.

"OTE is responsible to CEZ and other registry users for the safety of deposited CO2 allowances, just like banks are responsible for the safety of financial deposits," CEZ spokeswoman Eva Novakova said.

"We expect OTE in the immediate future to publicize details of the entire incident and to return back to our accounts the illegally transferred allowances," Novakova said.

The timing and method how stolen allowances or their replacements will be reincorporated into the trading system is still being discussed throughout Europe and in individual national registries, OTE's Stastny said.

Last week following cyber theft of emissions allowances in the Czech Republic, Austria and Greece, the European Commission said it was halting spot market trading of the allowances until at least Jan. 26, but trading still hasn't resumed.

"The wide preference is for quality over speed," Maria Kokkonen, spokeswoman for climate issues at the commission, told Dow Jones Newswires Thursday.

Experts from the commission and member countries will talk Friday afternoon, Kokkonen said.

At 1258 GMT CEZ shares were trading down 0.2% at 845 koruna ($47.8), in line with the broadly lower market.

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