As news reports confirm the next round of nuclear talks between Iran and the west will take place in Vienna, doubts have been raised in Tehran about the position of Ayatollah Ali Khamenei on the 24 November Geneva accord.

Recently, a few Iranian hardline politicians have spoken of the leader's opposition to the accord. A member of parliament's national security committee, Javad Karimi Ghodousi, has even emphasised that at a meeting with high-ranking government officials, the leader blamed the nuclear negotiations team for "not insisting on Iran's nuclear rights".

The publication of news reports such as this has not yet produced any reaction from the leader's associates, despite the fact that within Iran's regime there is very deep sensitivity about the validity of what is attributed to Khamenei.

We shouldn't view the lack of reaction as accidental. I believe the posture conveys a specific meaning: contrary to the image that has emerged among many observers, the nuclear negotiators of Hassan Rouhani's administration enjoy only very fragile support from the leader.

Just a few days prior to the accord, Khamenei said that he was not optimistic about the current nuclear talks with the west but that he believed there was "no harm in trying this".

In recent years, the leader has, in at least five separate instances, criticised the "retreat" of the nuclear negotiators during Mohammad Khatami's administration, repeating that the only result of this retreat was to increase the west's expectations of Tehran. Crucially, these negotiations were conducted by Rouhani, and led to the suspension of uranium enrichment in 2003. During his presidential election campaign, Rouhani responded to those who criticised his role in the negotiations under Khatami by reminding people that the supreme leader had expressly supported the results of the talks at the time.

Despite this, Rouhani had revealed some astonishing facts about the leader's complicated attitude towards the 2003 accord in his book National Security and Nuclear Diplomacy. Rouhani writes that, prior to signing the agreement with the foreign ministers of Britain, France and Germany – which ultimately became known as the Saad Abad agreement – he contacted the office of the supreme leader to learn of the latter's course of action, but was met with absolutely no response. He went ahead and signed the agreement on the assumption that Khamenei was not against it. It was this very same agreement that became the subject of continuous criticism from Khamenei's appointees and, after a few years, the leader himself.

There is no doubt that after the enactment of serious oil and financial sanctions against Iran in the summer of 2012, which Khamenei characterised as "savage", he came to the conclusion that there was no alternative but to reconsider the country's nuclear policy.

Now there is no doubt that Khamenei expects Rouhani to strive to lift the sanctions against Iran. But he does not want to share responsibility for any retreat from the nuclear programme. This is likely to be the reason he is not keen to deny recent reports about his opposition to the Geneva agreement.

The alarming meaning of such behaviour becomes clear when you remember that supporting the nuclear talks of Rouhani's administration is not the only option on the leader's table. Western negotiators should be aware that while Khamenei is deeply in need of the lifting of international sanctions, if he comes to the conclusion that the political costs of nuclear talks far outweigh the economic benefits they can bring, he will once again put an end to them.

Should that happen, he will undoubtedly state as loudly as possible that he was never in favour of the Geneva accord right from the beginning.

• This article was amended on 4 February 2014, changing the spelling of the the Saad Abad agreement from Saadat Abad.

