Officials at the Czech Republic's Temelin nuclear power plant say about 2,000 liters of mildly radioactive water leaked from the facility earlier this week.
A plant spokesman Thursday said the leak occurred after an employee forgot to close a valve. He said contaminated water flowed to a special tank, preventing any of the liquid from contaminating the environment.
This is the latest incident reported at the troubled plant about 60 kilometers from the Czech-Austrian border.
Austrian officials expressed surprise and anger over a delay in the announcement of the problem, particularly because Austrian Chancellor Alfred Gusenbauer was in Prague Tuesday for talks about the plant.
Austrian environmentalists promised to continue weekly border blockades as they press for the plant's shutdown.
Earlier in the week, Czech and Austrian leaders agreed to create a joint parliamentary commission with representatives from both countries to examine Temelin's safety record.
The two countries have been at odds over the plant since it opened in 2000. Austrian environmentalists demand its closure because of security concerns. Czech officials insist it is safe.
Some information for this report was provided by AFP and AP.