"Germany supports Lithuania in that higher security criteria must be observed," Merkel said in a joint news conference with Lithuanian President Gitanas Nauseda in Berlin on Wednesday.
"The European Union must watch (to ensure) that this Astravyets plant meets all safety standards and poses no risk," she said.
The Astravyets plant is located some 50 kilometers from Vilnius and less than 30 kilometers from Belarus' border with Lithuania.
Nauseda said the facility is being built without observing international security standards and that the choice of the site was driven by geopolitical rather than economic considerations.
"We are very much asking for help from our EU friends in ensuring that this power plant complies with all the necessary safety standards before it starts functioning," he said.
Belarus categorically rejects Lithuania's allegations.