Iran’s foreign minister has taken to the social media forum Clubhouse to answer questions in front of 8,000 people, in a move regarded by some as showing an unprecedented degree of openness but denounced by others as a fix in which unwelcome queries were not permitted.

Javad Zarif is the latest in a line of politicians to try out a medium that is proving increasingly popular in Iran amid a growing demand for political debate and discussion.

Although observers viewed Zarif’s presence as a further sign that he is testing the water prior to a potential run in the June presidential elections, he again swore he had no intention of standing and insisted he did not have the personal capabilities required.

The session had been billed as focusing on the controversial 25-year agreement between Iran and China signed at the weekend, but the questions ranged wider with the foreign minister staying until after midnight – despite admitting his bedtime was usually 10pm.

Zarif revealed he did not have an iPhone, and said: “I am not rich like the rest of you and I only managed to get the beta software that allows Androids to use Clubhouse two hours ago.” The software has been downloaded 20,000 times in Iran, since iPhones are beyond the reach of most ordinary Iranians.

Afterwards, a lively debate took place on social media over the degree to which the discussion had been manipulated to give an artificial sense of democratic participation.

Some claimed Zarif answered challenging questions, including about Iran’s power structure, while others said those who participated had been carefully vetted in advance. There was particular anger that Farsi-speaking journalists working for overseas outlets were not allowed to ask questions.

Defenders of the event pointed out that the New York Times and the US-based host of a well-regarded podcast on Iran did question Zarif.

Farid Modarresi, the journalist that chaired the meeting, said afterwards opponents of the regime and the Farsi-language journalists working outside Iran had been barred from speaking, but this was a decision not taken by the ministry of foreign affairs.

One critic, Gissou Nia, from the Atlantic Council, said on Twitter: “ … iPhone using elites posing questions to a potential candidate on Clubhouse is not an adequate substitute for free expression of actual political parties (which Iran does not have). CH convos are interesting but can give the appearance of free debate where there is none.”

With suspicions rife that Iran had sold its sovereignty to China by signing a 25-year-long cooperation agreement, Zarif defended the deal, insisting it “does not create any obligation for either party”.

Referring to the financial value of the deal, he said it “has no number”, and “does not cede any territory or even a point. There has been no pressure on the Iranian foreign ministry to sign the document.”

He added that Iran was not seeking to look exclusively east, but wanted connections east and west.

Zarif spent part of his time attacking a semi-fictional Iranian TV spy series called Gando, which implies some in the nuclear deal negotiating team were weak or spies. He said his life would have been easier if he was just allowed to get on with his job.

He again insisted the US had to move its position for talks on Iran coming back into full compliance with the nuclear deal to start, but said the grounds existed for choreographed mutual compliance so long as Iran was able to verify US sanctions were being lifted.

Joe Biden has hired Richard Nephew, an expert on Iran sanctions, and it is thought he is going through the painstaking process of classifying the sanctions so a sequenced and conditional lifting can take place in return for specific actions by Tehran to come back into compliance. Iran has reduced the level of inspections, increased its uranium stockpile, raised the level of enrichment and used increasingly sophisticated centrifuges.

Informal indirect talks have been under way with the EU acting as mediators. Angela Merkel, the German chancellor, and Emmanuel Macron, the French president, spoke with the Russian president, Vladimir Putin, at the start of the week.

The Russian foreign minister, Sergei Lavrov, said there were encouraging signs coming from the Biden administration. But there is growing frustration on the left of the Democratic party that Biden is delaying making any move for fear of alienating Congress, when urgency may be required as a result of the probability of a hardliner being brought in by the Iranian elections.

Others argue that the politics of the next president is not critical since all major decisions are taken by the supreme leader, Ayatollah Ali Khamenei, and his circle.