Iran "must never acquire a nuclear weapon," the British foreign secretary asserted on Wednesday.
"Iran is further expanding their nuclear programme," James Cleverly said on Twitter, adding that this was "yet more evidence of the danger the regime poses to global security."
"A regime that brutally oppresses its own people at home will surely threaten our friends and allies abroad. Iran must never acquire a nuclear weapon," he added.
Cleverly's remarks followed a joint G-7 statement condemning Iran's decision ealier this week to ramp up uranium production at the underground Fordow nuclear facility in response to a resolution passed by the UN's nuclear watchdog.
The International Atomic Energy Agency's (IAEA) 35-member board of governors had asked Iran last week 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 weapons-grade material but is still far higher than what Iran agreed to enrich under the 2015 nuclear deal.