Euratom told Reuters that Niger was the second-largest supplier of natural uranium to the European Union last year.
It said utilities in the bloc had enough uranium inventories to fuel its nuclear power reactors for three years.
"If imports from Niger are being cut, there are no immediate risks to the security of nuclear power production in the short term," said Euratom.
France said on Tuesday it would evacuate French and European citizens after the overthrow of the country's democratically elected government.
The EU's executive European Commission also said the 27-nation bloc had "sufficient inventories of uranium to mitigate any short-term supply risks".
"Medium and long-term, there are enough deposits on the world market" to cover EU needs, a spokesperson for the executive said.
Euratom said that in 2022, Niger delivered 2,975tU of natural uranium, or 25.4% of the EU's supplies. Kazakhstan was the biggest supplier for the bloc, with Canada third.
The agency said natural uranium equivalent in inventories owned by EU utilities last year totalled 35,710tU, compared to average annual consumption of around 12,500tU.
It said the bloc could diversify imports in up to three years, including from currently idled production sites in Canada, Australia and Namibia, as well as from new deposits.
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