Four Iranians suspected of involvement in a botched bomb plot targeting Israeli diplomats in Bangkok were members of an exiled Iranian opposition group which wanted the incident to reflect badly on Teheran, Syedsulaiman Husaini, Shia leader of Thailand, said on Sunday.

He claimed the four belonged to the Mujahedin-e Khalq Organisation (also known as MEK, MKO and the People's Mujahedeen Organisation of Iran, or PMOI) which aims to overthrow the current Iranian government.

The MEK has been on the US Department of State’s list of foreign terrorist organisations since 1977.

Thai authorities and security agencies were not familiar with the group, said Mr Syedsulaima, who is also director of the Islamic studies centre at Al Mahdi Institute and former president of the Iran University Alumni Association.

The Islamic scholar said the bomb incident was unlikely to be the work of the Iranian government as speculated because Bangkok and Teheran have good bilateral relations.

A secret report by Iran’s security agency also indicated that the Iran nationals linked with Bangkok’s latest  bomb plot were members of the MEK, reports said.

Formed in the 1960s, the organisation participated in Iran’s 1979 Islamic revolution that replaced the country's pro-Western ruler, Shah Mohammad Reza Pahlavi, with a Shi'ite Islamist regime led by the Ayatollah Khomeini. The MEK, whose ideology mixes Marxism and Islam, was expelled from Iran two years later after trying to stage an armed uprising against Khomeini.