Iran said Wednesday it will boycott next week's Frankfurt Book Fair after organisers invited the controversial author Salman Rushdie, whom Iranian scholars said should be killed, as a guest speaker.

The foreign ministry said the fair had, "under the pretext of freedom of expression, invited a person who is hated in the Islamic world and create the opportunity for Salman Rushdie... to make a speech".

It said the Islamic republic "strongly protests" Rushdie's appearance and had decided against participating in the fair, which is one of the world's largest such events.

The ministry called on other Muslim nations to join its boycott.

For his part, Deputy Culture Minister Abbas Salehi said:"Fair officials chose the theme of freedom of expression but they invited someone who has insulted our beliefs."

Rushdie, a Muslim and British citizen who lives in the United States, was made subject of a 1988 fatwa (religious edict) that called for his killing after his fourth novel, "The Satanic Verses," was published.

The Islamic republic's founder, Ayatollah Ruhollah Khomeini, issued the order after he and many others in the Muslim world said Rushdie had depicted Muslim prophet Mohammed irreverently.

The fatwa forced the writer into hiding and led the British government to place Rushdie under police protection. In recent years, the author has attended many public events though sometimes cancelled at short notice.

Khomeini died in 1989 but his successor supreme leader Ayatollah Ali Khamenei said in 2005 that the fatwa still stands, describing Rushdie as an apostate who can be killed with impunity.