The world's first next-generation pressurised water reactor being built in Finland could be further delayed and may now only start up in 2012, Finnish energy group Teollisuuden Voima (TVO) said Friday.

"Based on the present time schedule information received from the plant supplier, Areva-Siemens, the reactor plant civil construction works will take several months longer than earlier estimated," TVO said in a statement, adding: "The start-up of the plant may be postponed until 2012."

The reactor, being built at the Olkiluoto power plant in southwestern Finland, was originally scheduled to start up in 2009 but due to major delays the start was postponed to 2011.

As late as Thursday, project director Jouni Silvennoinen told reporters the reactor would begin producing electricity in "mid-2011."

However, in Friday's statement he said: "Despite the fact that a lot has been done, additional delay postponing the start-up of the plant has occurred. The plant supplier is naturally responsible for the time schedule and possible cost increase."

He added TVO had not agreed with Areva to split losses, but was in constant negotiations with the French company about the project and its schedule.

The reactor will be Finland's fifth nuclear reactor. Some 25 percent of electricity consumed in Finland is produced in nuclear power plants.