US Secretary of State John Kerry and his Iranian counterpart Mohammad Javad Zarif are back at the negotiating table again. Talks over Tehran's nuclear program resumed on Monday, as world powers try to reach a framework agreement by the end of March — for a deal, which would curtail, but not end, the Islamic Republic's enrichment activities in exchange for economic sanctions relief.

Now a senior Saudi official has spoken out against the potential agreement, warning it could encourage other states in the region to develop atomic fuel. Speaking to the BBC on Monday, Prince Turki al-Faisal, Saudi Arabia's former intelligence chief, said that the country would seek the same right as Iran: "I've always said whatever comes out of these talks, we will want the same."

"So if Iran has the ability to enrich uranium to whatever level, it's not just Saudi Arabia that's going to ask for that."

He continued: "The whole world will be an open door to go that route without any inhibition, and that's my main objection to this P5+1 process."

The warning came as Kerry and Zarif held nearly five hours of talk in the Swiss city of Lausanne, after which the Iranian delegation was due to travel to Brussels for meetings with European ministers, with talks to resume on Tuesday. However a senior US official cast doubt on whether the deadline for a framework agreement could still be met, telling reporters: "Iran still has to make some very tough and necessary choices to address the significant concerns that remain about its nuclear program."

The Saudi royals are by far from the only voices of displeasure at how the talks are progressing. Last week, 47 Republican senators signed an open letter to Iran's leaders, dismissing "any agreement regarding your nuclear weapons program that is not approved by the Congress as nothing more than an executive agreement between President Obama and Ayatollah Khamenei." A week earlier, in a speech to Congress, Israeli Prime Minister Benjamin Netanyahu described the talks as "a countdown to a potential nuclear nightmare."

But Riyadh has been one of the principal sources of regional resistance to a nuclear deal. Two weeks ago, after the last round of talks ended, Kerry's next stop was Saudi Arabia, where he assured America's allies in the Gulf that Washington would not "take its eye off Iran's destabilizing actions in places like Syria, Lebanon, Iraq and the Arabian peninsula, Yemen particularly." An agreement with Tehran would be no "grand bargain," he insisted.

Saudi Arabian officials have expressed concern over Iran's growing influence in Iraq, where it is aiding Shia militias in their bid to retake the city of Tikrit from the Islamic State in the city of Tikrit. Iranian General Qasem Soleimani of the Revolutionary Guards' elite Quds Force is in Salahuddin province, where it has been reported that Tehran is taking a leading role in the operation.

"The situation in Tikrit is a prime example of what we are worried about,' said Prince Saud al-Faisal, the Saudi foreign minister, after meeting with Kerry on March 5. "Iran is taking over the country."

On Monday, Prince Turki al-Faisal also called Iran a "disruptive player" in Yemen, Syria, Iraq, Palestine and Bahrain.

There have long been ideological and political tensions between Sunni Saudi Arabia and Shia Iran, and these have intensified recently over the Houthi Shia militias in Yemen, which has received military and financial support from Tehran, and the rise of the Islamic State.

In a recent interview, Middle East analyst Karim Sadjadpour of the Carnegie Endowment in Washington said that it was unlikely that Saudi Arabia and Iran would fight IS together, citing fundamental disagreements as to the root causes of the group's growth. "To Riyadh, ISIS's (IS's) rise is attributable to the repression of Sunnis in Syria and Iraq at the hands of Iran and its Shiite clients," Sadjadpour said. "To Tehran, ISIS's rise is attributable to the financial and ideological support of Gulf Arab countries, namely Saudi Arabia."

Fears that the regional rivalry could spill over into a nuclear fuel race were furthered when, just as Kerry and Zarif met for talks at the beginning of the month, Saudi Arabia signed a nuclear cooperation agreement with South Korea. According to Saudi state media, a memorandum of understanding calls for South Korea to build two nuclear reactors in Saudi Arabia, with a contract costing $2 billion.

It has also been reported that Saudi Arabia and state-owned companies from Argentina have set up a joint venture company called Invania to develop nuclear technology. According to the Saudi Gazette, Invania was established under a nuclear cooperation agreement between the two countries in 2011.

Prince Turki al-Faisal's latest comments could be perceived as an attempt to upset the Iran talks. Speaking to VICE News, Professor Arshin Adib-Moghaddam of the School of Oriental and African Studies at the University of London, and author of On the Arab Revolts and the Iranian Revolution: Power and Resistance Today, said: "There are several stakeholders that have tried to prevent a peace deal on Iran's nuclear issue. Netanyahu on the one side and the Saudi state on the other. Every threatening scenario that is being invented is meant to complicate the negotiations."

He continued: "Even if Saudi Arabia and other states would want to master the full nuclear fuel cycle then this is not a problem per se if adequate international safeguards are instituted. This requires regional cooperation and a new global nuclear energy infrastructure. Turki al-Faisal and others may want to point to solutions rather than to problems."

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