Britain on Thursday approved the visit to the country of Hizbullah official Ibrahim Moussawi to address a seminar on political Islam at the University of London's School of Oriental and African Studies.
The March 25 trip will mark the first official visit of a Hizbullah representative to the UK since the European boycott of the guerrilla group was lifted in 2005.
Conservative think tank, The Center for Social Cohesion (CSC), wrote to Home Secretary Jaqui Smith to protest the decision, and said it would instruct lawyers to seek an arrest warrant for Moussawi if he is allowed into the country.
CSC director Douglas Murray said the Home Office should apply its policy of banning entry to those who "stir up tension and provoke others to violence," which was recently used to bar the Dutch lawmaker and Islam critic Geert Wilders.
Murray expressed concern that the government "finds it acceptable that an individual who incites hatred against the Jewish people and of Israelis should be permitted to enter."
CSC researcher Alexander Meleagrou-Hitchens called Moussawi "a member of a terrorist group that is ideologically devoted to the destruction of Israel and the extermination of Jews worldwide; a group which murders political opponents as a matter of policy and terrorizes members of the Lebanese population who dare to defy them."
The decision to approve Moussawi's entry comes a week after Bill Rammell, the Foreign Office minister for the Middle East, told the British Parliament that his government would hold discussions with Hizbullah's political wing.
Rammell said that decision was made "in the light of more positive developments in Lebanon, and the formation of the national unity government in which Hizbullah is participating."