VATICAN CITY (Reuters) - Pope Benedict apologized on Saturday to victims of child sex abuse by Irish clergy, saying he felt "shame and remorse."

"You have suffered grievously and I am truly sorry," he said in an unprecedented letter which addressed the abuse of minors in Ireland.

In the letter, the pope also announced a formal Vatican investigation of Irish dioceses, seminaries and religious orders affected by the scandal. He said he was willing to meet victims to acknowledge their suffering personally.