BERLIN, Nov 30 - German Foreign Minister Guido Westerwelle said on Monday that Iran would face new international sanctions if it builds more uranium enrichment plants.

"What is clear is that if Iran rejects the hand that has reached out, it must expect heavier sanctions," Westerwelle said in a statement.

"Iran must know that the international community's patience is not unlimited," he added.

"I call on Iran to work with the international authorities handling nuclear matters and fulfil its international obligations, immediately and unconditionally."

Iran announced on Sunday plans to build 10 more nuclear enrichment plants following a vote of censure against Tehran by the International Atomic Energy Agency.

The move sparked strong reactions from the United States and France as well as Germany.

Iran's atomic chief Ali Akbar Salehi said Friday's IAEA resolution censuring Iran for building a second nuclear site near the holy city of Qom had prompted the decision to build more sites, in addition to its existing one at Natanz.

Western powers led by Washington want Iran to come clean on its uranium enrichment programme which they suspect is aimed at building atomic weapons, while Tehran says it is for purely peaceful purposes.

The West wants Tehran to agree to an IAEA-brokered deal which envisages sending its current stock of low-enriched uranium abroad for conversion into reactor fuel.

Iran maintains it has the right to enrich uranium as it is signatory to the Non-Proliferation Treaty (NPT).