Iran has threatened to boycott the London Olympics unless the organisers replace the official logo, which Tehran claims spells out the word "Zion".

The logo, a jagged representation of the year 2012, has been said by its critics to resemble many things, from a swastika to a sexual act, but the Iranian government argues it represents a veiled pro-Israeli conspiracy.

In a formal complaint to the International Olympic Committee, Tehran has called for the graphic to be replaced and its designers "confronted", warning that Iranian athletes might otherwise be ordered to stay away from the London Games.

According to the state-backed Iranian Students News Agency, which is frequently used to convey official pronouncements, the letter says: "As internet documents have proved, using the word Zion in the logo of the 2012 Olympic Games is a disgracing action and against the Olympics' valuable mottos.

"There is no doubt that negligence of the issue from your side may affect the presence of some countries in the Games, especially Iran which abides by commitment to the values and principles."

The letter, from the country's national Olympic committee, leaves unclear what "internet documents" it is referring to.

Amid the popular uproar that accompanied the unveiling of the logo in 2007, there were some claims, particularly on conspiracy-oriented websites, that its constituent shapes could be rearranged to make the world "Zion" and some animations were posted on YouTube showing how to do it.

An IOC official confirmed that the Iranian letter had been received but said: "The London 2012 logo represents the figure 2012, nothing else."

A spokesman for the London Olympic organising committee added: "It was launched in 2007 following testing and consultation. We are surprised that this complaint has been made now."