Soon after senior Iranian lawmakers rejected on Saturday any possibility of Teheran shipping uranium abroad for further enrichment, a move which intensifies pressure on the government to reject the UN-backed plan altogether, an advance copy of a Der Spiegel interview with Russian President Dmitry Medvedev showed that Moscow does not rule out joining an international effort to isolate the Islamic republic through harsher sanctions.
"If an agreement is reached on programs for the enrichment of uranium and its use in Iran for peaceful means, then we will gladly participate in these programs," Medvedev said in a copy of the interview which was released on Saturday and obtained by Reuters.
"If the Iranian leadership takes a less constructive position, then anything is possible in theory," he continued. He added that "we wouldn't want this to end with international sanctions because sanctions, as a rule, take us in a very complex and dangerous direction. But if there is no movement forward, nobody is ruling out such a scenario."
Earlier on Saturday, prominent conservative lawmaker Alaeddin Boroujerdi said Iran would not ship its low enriched uranium abroad in a single batch or in several shipments - a compromise suggested by some government officials - under any circumstances.
"Nothing will be given of the 1,200 kilograms (of low enriched uranium) ... to the other side in exchange for 20 percent enriched fuel, not in one batch nor in several. It is out of question," the semiofficial ISNA news agency quoted Boroujerdi as saying Saturday.
The UN-brokered plan required Iran to send 1.2 tons (1,100 kilograms) of low-enriched uranium - around 70 percent of its stockpile - to Russia in one batch by the end of the year, easing concerns the material would be used for a bomb.
After further enrichment in Russia, France would convert the uranium into fuel rods that would be returned to Iran for use in a reactor in Teheran that produces medical isotopes. Fuel rods cannot be further enriched into weapons-grade material.
Boroujerdi added that Iran's ambassador to the UN nuclear watchdog, Ali Asghar Soltanieh, was currently "in talks to find an approach for the issue."
Iran had previously indicated that it may agree to send only "part" of its stockpile in several shipments. Should the talks fail to help Iran obtain the fuel from abroad, Iran has threatened to enrich uranium to the higher level needed to power the research reactor itself domestically.
The Teheran research 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 southwestern Iran. Enriching uranium to even higher levels can produce weapons-grade materials.
The United States and its allies are unlikely to accept anything substantially less than the original plan, which aimed to delay Iran's potential ability of making nuclear weapons by at least a year by divesting Iran of most of its enriched uranium and returning it as research reactor fuel.
If 70 percent of Iran's uranium is exported in one shipment - or at the most two shipments in quick succession - Teheran would need about a year to produce enough uranium to again have the stockpile it needs for a weapon.
While the Iranian government is still considering the UN plan, the hardening posture of Iranian lawmakers has raised strong doubts that Teheran will approve the deal.
Another conservative lawmaker, Hossein Naqvi Hosseini, said Iran had three options to procure fuel for its reactor; to buy the fuel from other countries; to accept the UN-brokered plan; or to enrich uranium to a higher level domestically and produce the required fuel itself.
"The countries proposing ... are not trusted by the Islamic Republic of Iran because they didn't carry out their obligations to us in the past. Therefore, the second option is out of question," ISNA quoted Hosseini as saying.
"Exchange of uranium in return for fuel is out of question," another conservative lawmaker Ali Aghazadeh was quoted by ISNA as saying. "We have reached this point ourselves and we need to continue the path ourselves. It is their (US and its allies) obligations to give us fuel. If they fail to do so, we will supply it ourselves."
Iran has not formally rejected the UN-backed plan outright and Boroujerdi says the Supreme National Security Council, the country's top security decision-making body, is deliberating over the proposed deal.
Iran has officially asked for more talks on the issue and some hard-liners say they should receive the nuclear fuel first before shipping out the enriched uranium stocks.