TEHERAN - With exactly a week left before the deadline for a final agreement to limit Iran's nuclear programme, the country's supreme leader appeared to undercut several of the central agreements his negotiators have already reached with the West.
In a speech broadcast live on Iranian state television on Tuesday, Ayatollah Ali Khamenei made his strongest statements yet in demanding that most sanctions be lifted before Teheran dismantles part of its nuclear infrastructure and before international inspectors verify that the country is beginning to meet its commitments.
He also ruled out any freeze on Iran's sensitive nuclear enrichment for as long as a decade, as a preliminary understanding announced in April stipulates, and he repeated his refusal to allow inspections of Iranian military sites.
US officials said they would not be baited into a public debate with the Ayatollah, who has the final word on nuclear matters. But with Western foreign ministers already hinting that the negotiations may go past the June 30 deadline, both US and European officials have recently expressed concern about the possible effects of the Ayatollah's statements.
Even if the remarks were made chiefly to mollify hard-liners and military leaders, they say, they could sharply limit the flexibility of Iran's chief negotiator, Foreign Minister Mohammad Javad Zarif, as he heads into the week when the most difficult concessions are likely on both sides.
It is possible, outside experts say, that the Ayatollah's statements over the past two months, seemingly stepping back from major commitments made by Mr Zarif's team, are choreographed to bolster Iran's negotiators, who can argue that they cannot deviate from the supreme leader's strictures.
"My best judgment is that this is about leverage," said Mr Cliff Kupchan, the chairman of Eurasia Group, a political risk research and consulting firm in Washington. "I think what he's shooting for is the most sanctions relief he can get as soon as he can get it, and the least intrusive inspection regime going forward."
One of the Ayatollah's remarks suggested that a central premise of the deal - that sanctions would be lifted only in close coordination with Iran's dismantlement of centrifuges and reduction of its stocks of low-enriched uranium - is not possible.
In his speech, he said Teheran does not accept the "strange formula" for removing the sanctions, adding that "removing the sanctions must not be dependent on implementing Iran's commitments".
He also said verification of Iran's actions by the International Atomic Energy Agency (IAEA) was out of the question. "We have said from the first place that we want cruel sanctions to be lifted... You cannot ask us to fulfil our commitments and wait for the IAEA's confirmation for removing the sanctions. We completely disagree with it."
The Ayatollah also vowed to maintain an active nuclear programme for peaceful purposes.
NEW YORK TIMES