Iran said on Sunday it is fully prepared to enrich uranium at any level and with any amount, in further defiance of U.S. efforts to squeeze the country with sanctions and force it to renegotiate a 2015 nuclear deal with world powers.

In a news conference broadcast live, senior Iranian officials said Tehran would keep reducing its commitments every 60 days unless signatories of the pact moved to protect it from U.S. sanctions.

"In a few hours the technical process will come to an end and the enrichment beyond 3.67 percent will begin," said Behrouz Kamalvandi, the spokesman for Iran's Atomic Energy Organization.