Iran will only sign a nuclear deal with six world powers if all sanctions are lifted on the same day, President Hassan Rouhani said in a televised speech. (Reuters)

Iran’s supreme leader expressed pessimism Thursday about a deal reached last week with six world powers to restrict the country’s nuclear program, saying he neither supports nor opposes the accord and demanding that all economic sanctions be lifted immediately upon any final agreement.

The remarks by Ayatollah Ali Khamenei, Iran’s ultimate religious and political authority, raised the prospect that talks on a final accord, following last week’s framework agreement, could bog down over what he described as “the details” ahead of a June 30 deadline.

In a televised speech marking Iran’s National Day of Nuclear Technology, Khamenei also ruled out any “extraordinary supervision measures” over Iran’s nuclear activities and said that “Iran’s military sites cannot be inspected under the excuse of nuclear supervision,” the Associated Press reported. But he also repeated his denials that Iran has any intention of building nuclear weapons, which he has declared to be forbidden by Islam.

In a separate speech earlier, Iranian President Hassan Rouhani took the same position on economic sanctions as the supreme leader, saying that all of them “must be lifted immediately” once a final nuclear deal is implemented following talks under the framework agreement.

Iran’s Supreme Leader Ayatollah Ali Khamenei, seen here in a meeting with religious poets, has said that he “is neither for nor against” the deal. (Handout/via AFP/Getty Images)

“We will not sign any agreement unless all economic sanctions are totally lifted on the first day of the implementation of the deal,” Rouhani said during a ceremony marking the nuclear technology day, which celebrates the country’s nuclear achievements, AP reported.

The United States, which negotiated alongside Britain, France, China, Russia and Germany to reach the framework deal with Iran, insists that sanctions must be phased out gradually in tandem with Iranian steps to comply with the accord.

Making his first public comments on last week’s accord, Khamenei noted that no “binding” agreement exists yet and asserted that “sanctions should be lifted completely, on the very day of deal,” once a final agreement is reached.

“All sanctions should be removed when the deal is signed,” he said, according to Reuters news agency. “If the sanctions removal depends on other processes, then why did we start the negotiations?”

It was not immediately clear whether Khamenei was seeking to assuage hard-liners in Iran who have vocally opposed the nuclear negotiations, or whether he was signaling his own deal-breaking reservations about the framework agreement. Khamenei has the final say on Iranian acceptance of any agreement.

Highlights of the Iran deal

Khamenei said he had faith in Rouhani’s negotiators but expressed suspicion of Washington, warning about its “devilish” intentions.

“I neither support nor oppose the deal,” he said, Reuters reported. “Everything is in the details. It may be that the deceptive other side wants to restrict us in the details.”

He added: “I was never optimistic about negotiating with America. . . . Nonetheless I agreed to the negotiations and supported, and still support, the negotiators.” As he spoke , a crowd chanted, “Death to America,” Reuters said.

Khamenei said the framework agreed reached April 2 “does not guarantee a deal” by the June 30 deadline “or even that the negotiations will continue to the end.”

He also denounced a State Department fact sheet issued shortly after last week’s talks concluded. The document laid out various restrictions on Iran’s nuclear program in exchange for the phased lifting of nuclear-related economic sanctions imposed by the United States and its allies.

“Americans put out a statement just a few hours after our negotiators finished their talks,” he said. “This statement, which they called a ‘fact sheet,’ was wrong on most of the issues.”

In his earlier remarks, Rouhani also called for an end to airstrikes in Yemen by a Saudi-led coalition aimed at halting the advance of Iranian-backed rebels, one day after Tehran reported that two of its warships were headed for the waters off Yemen.

Rouhani said the U.S.-supported bombing campaign in the Arabian Peninsula country could not succeed and that countries in the region should instead work toward a political solution, news agencies reported from Tehran.

“A great nation like Yemen will not submit to bombing. Come, let us all think about ending war. Let us think about a cease-fire,” Rouhani said in the speech, the agencies reported.

Saudi Arabia and a coalition that includes four other Arab states in the Persian Gulf have carried out airstrikes against the Iran-allied Houthi rebel movement for the past two weeks to try to drive the rebels back.

“Let us prepare to bring Yemenis to the negotiating table to make decisions about their future,” Rouhani said. “Let us accept that the future of Yemen will be in the hands of the people of Yemen, not anyone else.”

Coalition countries say they are supporting Yemeni President Abed Rabbo Mansour Hadi, who has fled the country, against a coup by the Houthis. They accuse Shiite powerhouse Iran of arming the group, a charge Tehran denies. The Houthis are followers of the Zaydi branch of Shiite Islam.

Rouhani’s comments came one day after Iran’s English-language Press TV reported that an Iranian destroyer and another warship were headed for the waters near Yemen.

Iranian Rear Adm. Habibollah Sayyari said the warships would be providing security for “Iran’s shipping lanes” and protecting the country’s “interests in the high seas,” according to Press TV. He said they will also seek to keep commercial ships safe from pirates.

U.S. Secretary of State John F. Kerry on Wednesday accused Iran of meddling in Yemen.

Speaking on the “PBS NewsHour,” Kerry said the United States was “very concerned” over Iran’s support for the Shiite rebels in Yemen. He said the United States was closely monitoring Iranian support for the rebels, including “supplies that have been coming from Iran” and “a number of [Iranian] flights every single week” into Yemen.

“We’re well aware of the support that Iran has been giving to Yemen,” he said. “And Iran needs to recognize that the United States is not going to stand by while the region is destabilized or while people engage in overt warfare across lines, international boundaries and other countries.”

Kerry said Washington, which has providing intelligence and logistical support for the bombing campaign and stepped up weapons sales to coalition states, is “not looking for a confrontation, obviously.”

“But we’re not going to step away from our alliances and our friendships, and the need to stand with those who feel threatened as the consequence of the choices that Iran might be making,” he added.

On the same day, Iranian Foreign Minister Mohammad Javad Zarif called on Pakistan during a visit to Islamabad to work toward a political solution, after Saudi Arabia asked Pakistan to join the coalition. Pakistan’s parliament is debating the Saudi request.

The diplomatic maneuvering came as the United States widened its support for the Saudi-led coalition, boosting weapons supplies and intelligence-sharing and carrying out the first U.S. aerial refueling mission of coalition fighter jets.

Col. Steve Warren, a Pentagon spokesman, told reporters Wednesday that the United States had conducted its first military intervention in support of the Arab coalition, the aerial refueling of F-16s from the United Arab Emirates and F-15s from Saudi Arabia. He provided no details, except to say the refueling did not take place over Yemeni airspace.

Analysts quoted by the Associated Press said Wednesday’s move by Iran to send warships to Yemeni waters was posturing by the regional powerhouse.

In Abu Dhabi, the U.A.E. capital, a leading partner in the coalition, Foreign Minister Sheik Abdullah bin Zayed al-Nahyan said Iran’s meddling in several Arab countries, including Yemen, left little hope for cooperation, the AP reported. He characterized it as part of a broader pattern of Iranian efforts to expand its influence in the region.

“It’s not about sectarianism. It’s about Iran believing in exporting the revolution. It’s a part of their regime, a part of their ideology. Until they choose to deal with us country to country, we will have suspicions,” he said, according to the AP.

Read more:

Who are the Houthis?

Yemen rebels stage raids on suspected opponents

Despite Saudi-led airstrikes, Shiite rebels continue to advance in Yemen

Al-Qaeda fighters overrun Yemeni military base, exploiting turmoil

Today's coverage from Post correspondents around the world