Iran's parliament speaker accused the West on Saturday of trying to cheat the country with a U.N.-drafted plan that would ship most of Iran's uranium to Russia for enrichment, raising further doubts about the likelihood Tehran will approve the deal.

The U.S. and its allies have been pushing the agreement as a way to ease their concerns that Iran is using its nuclear program as a way to covertly develop weapons capability.

The Iranian government, which insists its program is peaceful, has said it is still studying the U.N. agreement and will formally respond to the offer next week, but a growing number of Iranian officials have come out against the deal.

"Westerners are insisting on going in a direction to cheat and impose their will on us," Iran's semiofficial ISNA news agency quoted parliament speaker Ali Larijani as saying Saturday.

Larijani said Iran prefers to buy the nuclear fuel it needs for a reactor that makes medical isotopes rather than accept the U.N. plan, which would require Iran to ship around 70 percent of its low-enriched uranium to Russia for further enrichment.

The Tehran reactor needs uranium enriched to about 20 percent, higher than the 3.5 percent-enriched uranium Iran is producing for a nuclear power plant it plans to build in the country's southwest.

Iranian officials have said it is more economical to purchase the more highly-enriched uranium abroad than produce it domestically. But they have also warned the country will enrich uranium to the higher level needed to power the Tehran reactor if talks fail to help Iran obtain the fuel from abroad.

"They (Westerners) said we will give Iran 20 percent fuel if you give us your enriched uranium," Larijani told ISNA in an interview. "We don't see any link between the two."

He said there is "no logical or legal justification" to condition the delivery of nuclear fuel for the reactor on Iran's willingness to send its uranium abroad.

Iranian state media quoted an unnamed official close to Iran's negotiating team as saying Friday that the country was waiting for a response from world powers to its proposal to purchase nuclear fuel. The comments were a disappointment to the U.S., Russia and France, which negotiated the U.N. plan with Iran earlier in the week and had hoped to secure the country's approval by Friday.

Prominent conservative lawmaker Alaeddin Boroujerdi, who heads Iran's National Security and Foreign Affairs Committee, said the country would be better off buying nuclear fuel because it needs its low-enriched uranium for the power plants it plans to build.

"It is better to buy 20 percent-enriched nuclear fuel because we need our 3.5 percent-enriched uranium to fuel our nuclear plants, such as the 360 megawatt Darhovin plant," ISNA quoted him as saying Saturday.

Iran's deputy parliament speaker, Mohammad Reza Bahonar, has also dismissed the U.N. plan.

Although parliament will not vote on the agreement, the opposition from lawmakers reflects concerns that the plan would weaken control over its stockpiles of nuclear fuel.

The draft U.N. plan would require Iran to send 2,420 pounds of low-enriched uranium — around 70 percent of its stockpile — to Russia in one batch by the end of the year, French Foreign Ministry spokesman Bernard Valero said Thursday.

After further enrichment in Russia, France would have converted the uranium into fuel rods for return to Iran for use in the Tehran reactor, he said.

This would significantly restrain any covert arms pursuit, since 2,205 pounds is the commonly accepted amount of low-enriched uranium needed to produce weapons-grade uranium for a single nuclear warhead.

Based on Iran's present stockpile, the U.S. has estimated that Tehran could produce a nuclear weapon between 2010 and 2015, an assessment that broadly matches those from Israel and other nations.

President Barack Obama has stepped up diplomatic engagement with Iran since he took office in January in an attempt to ease international tension over the country's nuclear program. But he has also threatened harsher sanctions if Iran does not cooperate.

The U.N. Security Council has already passed three sets of sanctions against Iran for failing to suspend uranium enrichment, but the U.S. faces a serious challenge in convincing Russia and China to go even further because of their close ties to Tehran.

The president has called French President Nicolas Sarkozy and Russian President Dmitry Medvedev to reaffirm their commitment to a U.N.-backed plan that would ship most of Iran's uranium abroad for enrichment.

The three presidents endorsed the proposal this week as a means of calming fears in the West that Iran is developing a nuclear weapon. Iran has not said whether it will comply. The Tehran government insists its nuclear program is aimed at generating power and not building a weapon.

The White House said Saturday that Obama thanked Sarkozy and Medvedev for their help in addressing the issue and discussed the importance of implementing it soon.