IRAN’S president, Mahmoud Ahmadinejad, said on Thursday he would like to come to the London Olympics but would not be attending because Britain had “a problem” with him. His decision to stay away highlights a dilemma for the British government, which faces an unprecedented influx of leaders from unsavoury regimes for the opening ceremony on July 27.

Ahmadinejad made it clear he had been keen to travel to London to support Iran’s Olympic team. Speaking at Tehran’s Azadi sports complex, he told a group of athletes: “But unfortunately they have a problem with my presence. Otherwise I would have liked to have participated in the Olympics, and to have applauded our dear youth.”

Iran’s state media this week speculated that Ahmadinejad was unwilling to submit to the fingerprinting necessary to obtain a British visa — seeing this as an unacceptable and humiliating procedure. Downing Street will privately be relieved that Ahmadinejad is staying away. But other heads of state from controversial regimes will be coming to London, in what is turning into a growing public relations headache for David Cameron.

Some 120 heads of state have said they will attend the opening ceremony. It will be the largest top-level international gathering in diplomatic history, the UK Foreign Office believes. The number far exceeds the 87 leaders who travelled to Beijing in 2008. The foreign minister, William Hague, refused to disclose the guest list, as campaigners this week called on Britain to withdraw invitations to “dictators” from countries with poor human-rights records. Several are already on an EU blacklist; they include Zimbabwe’s Robert Mugabe, Syria’s Bashar al-Assad, and Belarus’s Alexander Lukashenko.

But other authoritarian leaders not on the list are likely to travel to London. Uzbekistan’s despotic leader Islam Karimov and his Turkmen counterpart Gurbanguly Berdymukhamedov both visited the Beijing Olympics in 2008. According to Hugh Williamson, director of Human Rights Watch’s Europe and central Asia division, the two post-Soviet republics are “absolutely in the category of the worst dictatorships in the world and the worst abusers of human rights”.

Williamson said he was not in favour of banning anyone from attending the Games. But he said Cameron should send a “very clear signal” on human rights by refusing to meet either Karimov or Berdymukhamedov in London. The prime minister should also raise the treatment of opposition demonstrators in Russia with President Vladimir Putin, he said.

It remains unclear if Putin will actually come to London. Moscow is sending more than 400 athletes to the Games and is hosting the 2014 Winter Olympics in Sochi. But Putin is displeased with Britain for granting asylum to Kremlin critics.

The former Europe minister Denis MacShane this week asked Hague to clarify who had not been “invited”. Hague has yet to reply. MacShane — a critic of the coalition’s business-focused foreign policy — said the list of heads of state not welcome at the Games should include Bahrain, Syria, China, Zimbabwe and Saudi Arabia.

Downing Street, however, has been reluctant to take a strong stand on human rights during the Olympics. Speaking 100 days before the Games, the culture minister, Jeremy Hunt, said Britain did not intend to use the event to “preach about our values”, arguing: “There are many other forums where that can happen.” The Foreign Office is wrestling with what to do about Olympic representatives from Syria and Bahrain.—The Guardian, London