A Romanian nuclear reactor closed down on Monday because of a technical problem was restarted on Wednesday, the national operator Nuclearelectrica said.

"The restarting operation was carried out in keeping with procedures and safety standards," the company said.

"There was no negative impact on the staff, the population or the environment," it added.

Reactor number 2 of the Cernavoda plant was stopped in order to fix a demineralised water leakage preventing the unit from running in optimal conditions, the national company had announced Monday.

Romania's only nuclear plant has two reactors using the Candu-type Canadian technology. They produce about 18 percent of the country's electricity needs.