All foreign bidders for a 49 per cent share in Bulgaria's Belene nuclear power plant had submitted improved offers on January 9, Reuters said the National Electric Company (NEC) announced.

The bidders included Italy's Enel, Germany's E.ON, and RWE, Czech CEZ and Belgium's Electrabel, which was owned by French utility Suez.

NEC, which would own the remaining 51 per cent of the nuclear power plant, had asked for improved offers regarding the role investors intended to play infuture management of Belene.

"All five bidders submitted improved offers," Reuters quoted a NEC spokeswoman as saying, though she refused to give further information.

Belene would be built by Russia's Atomstroyexport, with France's Areva and Germany's Siemens. The plant was expected to go into production after 2014.