There are signs of cracks in a reactor vessel at a second nuclear plant in Belgium, with the problems similar to those identified at another site, power generator Electrabel said on Thursday.

"First results from the investigation (at Tihange 2) show signs similar to those found at Doel 3," said the company, a unit of French giant GDF Suez.

Signs of "thousands of potential cracks" were found during inspections earlier this year of the base of the reactor vessel at Doel 3, near the northern city of Antwerp and which has been closed since June.

Tihange 2, near the southern city of Liege and using the same reactor vessel as Doel 3, was halted in August for investigation after the problems at Doel came to light.

"The investigation at Tihange 2 will continue and it will take several more weeks before we get definite answers. Tihange will remain halted in the meantime," a company spokeswoman said.

The reactor vessels, housing the nuclear core, were built in the 1970s by the Dutch firm Rotterdamsche Droogdok Maatschappij (RDM), which has since ceased business.

RDM equipped some 20 nuclear plants, half of them in Europe.

Earlier this year, the Belgian nuclear regulator said the problems in the Doel 3 reactor likely dated back to its construction and while there was little risk for the present, he felt "a malaise given the large number" of defects.

He added that he was sceptical that Doel 3 could be restarted.

The Fukushima nuclear disaster in Japan last year has increased the sensitivity over the safety of nuclear energy, with Germany deciding to phase out its plants.

The EU counts 147 reactors in 14 countries with more than a third of the total in France which depends almost entirely on nuclear generators for electricity.