Iran's top nuclear negotiator Ali Larijani on Tuesday deplored Russia's decision not to ship nuclear fuel to Iran as agreed, a move that delays the start of Iran's first nuclear power plant. "This [Russian decision] shows that there is no such thing as a guarantee to deliver nuclear fuel," the official Islamic Republic News Agency quoted Larijani as saying Tuesday. The Russian move, announced Monday, means that Iran's first nuclear reactor will not come on stream in September, as was scheduled. This is a major political blow to Iran, which expected the commissioned power plant to boost its position in long-running negotiations with the United Nations over its nuclear program. "Russians are extortionists," the Iranian lawmaker Rasoul Sediqi Bonabi said Tuesday. "Moscow has never been a reliable partner and will never be so in the future." Russia's federal nuclear agency, Rosatom, said Monday it was postponing the March shipment of nuclear fuel to Iran because the country had failed to pay for work on the Russian-built reactor outside this southern Iranian city. Iran rejected the Russian claim, saying it has fulfilled all its financial obligations. Rosatom spokesman Sergei Novikov told The Associated Press that the start of the reactor - scheduled for September - would be postponed by at least two months because the Iranians had made no payments since January 17. "The funding is two months behind, and that means a corresponding delay in schedule," Novikov said. "There is no money, and it's impossible to keep construction works going without money." But Larijani said Tuesday that Iran expected Russia to stick to its obligations. "Russia has to fulfill its promises on time," the official news agency quoted Larijani as saying. Larijani rejected reports that said Russia would not proceed with the Bushehr plant unless Iran suspends uranium enrichment, as the UN Security Council has repeatedly demanded. "We have not received such a message from Russia," he said. Reports from Moscow on Monday indicated that the underlying cause of the financial dispute was Russia's annoyance that Iran has spurned all diplomatic efforts to persuade it to stop enriching uranium - a process that produces the fuel for nuclear reactors and, taken to a higher degree, the material for atomic bombs. The United States and some of its allies accuse Iran of using its civilian nuclear program - of which Bushehr is the cornerstone - as a cover for seeking to build nuclear weapons. Iran denies this, saying the program is strictly for generating electricity and it requires enrichment to have an independent supply of fuel. Iranian newspapers said Tuesday that Iran's unhappy experience with Russia and the West left no doubt that it had to develop its own supply of enriched uranium. "Russia's behavior is the best reason for why Iran must insist on enriching uranium and producing nuclear fuel itself," the conservative daily Resalat said in an editorial. "You can't spend billions of dollars [on building a power plant] and then have to beg others for fuel." The government brought journalists to Bushehr on Tuesday to witness the inauguration of a pumping unit and other small features of the power plant. Vice President Gholamreza Aghazadeh, who is also the head of Iran's Atomic Energy Organization, was scheduled to perform the opening ceremony. But the inauguration was cancelled, apparently because of the Russian decision.