Fielding questions at a press conference, Szijjártó said the production of the reactor vessel had started on Thursday.

He added that the Paks II melt trap had been completed and would be delivered to Hungary in the summer.

Work on Paks II is "advancing on schedule" and the two new blocks at the plant, Hungary's only source of commercial nuclear power, could go online early in the coming decade, Szijjártó said.

A ceremony to mark the start of production of the reactor vessel took place at the foundry of Atomenergomash in Kolpino, on the outskirts of Saint Petersburg on Friday.

Deputy-CEO Andrey Sinakov said parent company Rosatom, the general contractor for Paks II, would make the plant's number 5 reactor block on time, while meeting all quality requirements. 

Responding to a question from MTI, he said a reactor generally took about three years to make.

Vitaly Polyanin, the project director for Paks II, said the investment was moving forward on schedule.