The United States says "time is running out" for Iran to address international concerns about its nuclear program.
The White House statement comes after Iran announced plans on November 29 to build 10 new uranium-enrichment plants.
In a statement, spokesman Robert Gibbs said "this would be yet another serious violation of Iran's clear obligations under multiple UN Security Council resolutions."
The move by Iranian President Mahmud Ahmadinejad comes just days after the UN nuclear watchdog rebuked Tehran for carrying out such work in secret.
Germany expressed "great concern." British Foreign Secretary David Milliband accused Iran of trying to "provoke" the international community.
Ahmadinejad said Iran should aim to produce 250-300 tons of nuclear fuel a year and that new, faster centrifuges should be used to reach that target.
Iran's atomic energy organization chief, Ali Akbar Salehi, said they would be built so that they would be protected from any military attack, for example in the "hearts of mountains".
State broadcaster IRIB said the location of five of the 10 new plants had already been decided and that work on these should start within two months.
In related news, Russia's energy minister has vowed a "quick completion" of Iran's first nuclear power plant.
Sergei Shmatko was speaking in Tehran on November 29 following talks with Iranian Oil Minister Masud Mirkazemi.
In mid-November, Shmatko said technical issues were causing delays in construction of the reactor at Bushehr and Russian state contractor Atomstroyexport would not finish work there by the end of the year as previously planned.
compiled from agency reports