Seán Ó Muireagáin is a Belfast freelance journalist who has worked for Irish language print and broadcast organisations including the television station TG4 and the Belfast newspaper . He was arrested by Israel near Ramallah in July 2003 in a case of mistaken identity and accused of being a Real IRA terrorist in Israel to engage in bombings. The events surrounding his arrest and release, and the role played by the British intelligence services, made international headlines and led to considerable criticism of Israel in the Irish and British media.

Ó Muireagáin was arrested on 12 July 2003 and questioned about his supposed involvement in the Real IRA, an Irish terrorist organisation. News of his arrest was widely reported in the British media on Sunday, 13 July. The arrest was trumpeted as an example of cooperation against terrorism between the British and Israeli intelligence services, the latter having arrested Ó Muireagáin following information from the former.

However it was discovered that the information from the British intelligence services was incorrect. While there allegedly is a Real IRA terrorist called Seán Ó Muireagáin, the Seán Ó Muireagáin arrested was a journalist reporting from Palestine for the Irish language newspaper . He was in the Palestinian area as part of a schools exchange programme between Palestinian schools and schools in Northern Ireland. Ó Muireagáin was also a peace activist with an Irish-Palestinian solidarity group.

Israel released Ó Muireagáin without charge on 16 July 2003, having held him without legal representation for a number of days. In a state of confusion, while the Israeli embassy in Dublin called the arrest "unfortunate", and the Israeli Prime Minister's spokesman told RTÉ radio that an error had been made, an Israeli Foreign Ministry spokesman told RTÉ that Ó Muireagáin may have been guilty but simply not had had the chance to link up yet with Palestinian terrorists. The confusion was heightened when it was suggested that Ó Muireagáin was a convicted Provisional IRA terrorist.

In a press conference in Belfast following his release, Ó Muireagáin stated that he had never had any association whatsoever with any Irish terrorist organisation and had never been convicted of being a Provisional IRA terrorist. He did have one criminal conviction in the 1980s but it was unconnected to anything to do with terrorism. Ó Muireagáin stated that the Israeli forces had finally accepted his innocence when he took a polygraph test confirming his story.

Israel's handling of the events surrounding his arrest, and the claims after his release that he was a convicted terrorist, were strongly condemned in both Northern Ireland and the Republic of Ireland. Former SDLP cabinet minister and terrorist critic Sean Farren stated prior to Ó Muireagáin's release: "Seán Ó Muireagáin is a well known Irish language activist who has devoted a considerable amount of time to promoting Irish language activities across the North."

The identity mix-up and British Intelligence's role in the mistaken arrest were viewed as another embarrassing blow to the British intelligence services, who were facing criticism over inaccuracies in dossiers (the so called Dodgy Dossier) prepared to justify Britain's role in the War on Iraq.