Belarus demanded on Thursday that Russia, which is building the country's first nuclear plant, take back a reactor shell after an accident during construction put the ex-Soviet country on edge.

A contractor working for Russian state nuclear agency Rosatom last month was moving the massive steel shell that encases a nuclear reactor when the crane malfunctioned and the structure hit the ground.

The public in Belarus, a country that was severely hit by fallout from the 1986 Chernobyl catastrophe in Ukraine, pressured President Alexander Lukashenko last week to announce that the shell must be replaced with a new one even if it has "the smallest scratch".

On Thursday Belarus Energy Minister Vladimir Potupchik said a government commission "made the decision to switch the reactor shell" and had sent the relevant demand to the Russian side.

Rosatom has argued that the shell is perfectly safe while Belarusians have accused authorities of covering up the July 10 accident, which went unreported for two weeks.

The incident came to light only after local activists expressed concern that the structure was no longer safe.

Rosatom's deputy chief Alexander Lozhkin was quoted by the agency as saying that the 330-tonne shell had merely "touched" the ground after sliding down from a four-meter height.

The plant -- which is being built in the western Belarusian town of Ostrovets, around 10 kilometres (six miles) from the Lithuanian border -- has been under construction since 2013. It is set to launch the first of its two 1,200 megawatt reactors in 2018.

Lithuania had already expressed concern about the project.