The UK, France and Germany on Tuesday denounced Iran's decision to expand its nuclear program in response to the UN's adoption of a resolution, according to a joint statement.
"By accelerating its production of enriched uranium, Iran has taken further significant steps in hollowing out the JCPoA," according to the E3 countries that accused Tehran of violating the Joint Comprehensive Plan of Action (JCPOA) requirements.
Iran announced its decision to ramp up the production of uranium at the underground Fordow nuclear facility in response to the resolution passed by the UN nuclear watchdog.
Referring to increased production of high enriched uranium, the statement said: "Iran's step is a challenge to the global non-proliferation system. This step, which carries significant proliferation-related risks, has no credible civilian justification."
It demanded that Iran "fully" employ its safeguards agreement under the Non-Proliferation Treaty.
"We will continue to consult, alongside international partners, on how best to address Iran's continued nuclear escalation," it added.
The Atomic Energy Organization of Iran, as cited by the state media, said it began to produce uranium up to 60% purity at the Fordow facility.
The UN watchdog's 35-member board of governors passed the resolution last week, asking Iran to urgently cooperate with its investigation into uranium traces found at three undeclared sites.
The enrichment up to 60% purity is still below the roughly 90% required for the weapons-grade material but still far higher than what Iran agreed to enrich under the 2015 nuclear deal.