(CNN) -- Iran's lead nuclear negotiator announced a tentative agreement was reached Friday over the implementation of plan that requires Tehran to limit its nuclear program, even as U.S. officials described the talks as ongoing.
The conflicting reports came as Iran wrapped up two days of talks in Geneva with the European Union, the United States, China and Russia over how put in place a deal that calls for Tehran to limit its nuclear activities in exchange or a softening of sanctions that have crippled its economy.
Negotiators from both sides appeared to make progress, with Iran's lead negotiator -- Abbas Araqchi -- telling state-run Press TV that the two sides reached a tentative deal. Neither Araqchi nor the top negotiator for the six world powers detailed the agreement.
If all sides accept the plan, an official announcement will be made within two weeks, Araqchi said, according to the official IRNA news agency.
But U.S. officials say while progress has been made, the agreement still needs to be finalized.
"The accurate description would be that they are ongoing. The negotiations are ongoing," State Department spokeswoman Jen Psaki said during a briefing in Washington.
The nuclear deal struck in November has been widely hailed as a successful interim measure to stave off an unwanted conflict over Tehran's nuclear program.
But after initially celebrating a diplomatic success, Iran has reportedly lashed out at the United States for making public a modified version of the agreement that they say does not reflect Tehran's interpretation.
Late last month, Iranian lawmakers drafted a bill that would force the government to enrich uranium up to 60% if new sanctions are imposed, state media reported.
The move came only days after bipartisan legislation was introduced in the U.S. Senate that would authorize new economic sanctions on Iran if it breaches an interim agreement to limit its nuclear program or fails to strike a final accord terminating those ambitions.
On Friday, the Senate moved toward a veto-proof majority supporting legislation authorizing new economic sanctions on Iran.
The bipartisan proposal introduced by Foreign Relations Committee Chairman Sen. Robert Menendez, D-New Jersey, and Sen. Mark Kirk, R-Illinois, now has 59 senators who have formally committed to support it, a senior Senate aide told CNN.
The aide said that the current informal count is even higher -- at 77 yes votes -- and that more are expected to come on board once the undecided are forced to vote. A two-thirds majority in both the Senate and House of Representatives is necessary to override a presidential veto.
President Barack Obama has threatened to veto any legislation that would authorize new economic sanctions on Iran, saying such a bill at this time would undermine delicate efforts to forge a lasting deal with Tehran.
The bill could come to the Senate floor for consideration during the week of Obama's State of the Union address on January 28 or the following week, said the aide, who spoke on condition of anonymity, citing the sensitivity of the issue.
The proposal would give Obama more than a year to engage in further diplomacy before any new sanctions would kick in against Iran's oil exports and other key areas of its economy, but sanctions would hit sooner if Iran cheats on the interim deal or fails to reach a final accord.
The United States and other Western powers believe Iran is attempting to build a bomb through uranium enrichment. But Tehran says its nuclear intentions are peaceful.
CNN's Chief National Security Correspondent Jim Sciutto reported from Washington; Chelsea J. Carter wrote from Atlanta. Mohammed Tawfeeq also contributed to this report.