Iran's president on Monday signed a bill to continue uranium enrichment, and limiting cooperation with the UN's nuclear watchdog, state news agency IRNA reported. On the other hand, Tehran announced it will begin building a new site to enrich uranium in March, moving ahead with a plan that defies international efforts to curb its nuclear development. The law on Safeguarding the Islamic Republic of Iran's Peaceful Nuclear Achievements signed by President Mahmoud Ahmadinejad calls for continued enrichment of uranium to 20 percent level, IRNA reported. Under the new law the government is “obliged to continue its efforts to produce fuel for the Tehran research reactor as well as continue the 20 percent enrichment (of uranium)... and to produce the fuel plates required for the reactor.” The law also stipulates that the government “cooperate with the IAEA (International Atomic Energy Agency) only under the framework of the Non-Proliferation Treaty's (NPT) general regulations.” It bans any cooperation that goes beyond the NPT requirements, the English language Press TV said on its website. Last year, Iran flouted international concerns by claiming it would build 10 new enrichment plants and Monday's announcement said the locations for the sites have now been determined but gave no details. “Construction of a new uranium enrichment site will begin by the end of the (Iranian) year (March) or early next year,” the chief of Iran's Atomic Energy Organization, Ali Akbar Salehi, said. “The new enrichment facilities will be built inside mountains.” Revelations a year ago of a previously undisclosed enrichment facility in a secret mountain base near the city of Qom, inflamed international suspicions over Iran's enrichment program and helped spur a fourth set of international sanctions in June. British Prime Minister David Cameron's spokesman Steve Field said that Salehi's announcement was a cause for concern. “The reports that we have seen this morning certainly do not give us any comfort that Iran is moving in the right direction,” Field told reporters Iran has an industrial-scale, internationally supervised enrichment site in Natanz, in central Iran, with around 6,000 operating centrifuges and as well as the smaller one under construction near Qom. Tehran said it needs 20 large-scale sites to meet domestic electricity needs of 20,000 megawatts in the next 15 years.