Activist Kate O'Sullivan managed to get through tight security to confront Mr Blair as he held a book signing in Dublin.
The 24-year-old from Cork claims to have queued for 90 minutes and went through airport style security - handing in all her belongings and going through a metal detector - before she attempted to arrest Mr Blair.
She says the former Prime was blasé about her accusations: "He didn't say anything, He just signed the book, he looked down and then looked at security."
Ms O'Sullivan, a member of the Irish Palestine Solidarity Movement, was detained for almost half an hour before she was cautioned by gardai.
Earlier, shoes and eggs had been pelted at Mr Blair as he arrived at the bookshop on O'Connell Street in Dublin city centre.