Visit to discuss Christian minority is one of the highlights of pontiff's four-day trip to Iraq, where Sistani has played a key role in tamping down tensions in recent decades

Pontiff to travel to shrine city of Najaf to meet Muslim authority figure during visit aimed at comforting Iraqi Christians and deepening interfaith relations

Pontiff's talks with Ali al-Sistani will implicitly recognize him as Shiite Islam's chief interlocutor over his rival, Iranian Supreme Leader Ali Khamenei

Ruhollah Zam, hanged last year for 'sowing corruption' and allegedly spying for France and Israel, was tricked into traveling to Iraq and detained by Revolutionary Guard

The question of succession after Grand Ayatollah Ali al-Sistani gains added importance for an Iraq deeply embroiled in US-Iranian tensions and gripped by anti-government protests

11 wounded by security forces as deadline nears for political blocs to agree on new premier; 4 rockets fired at base housing US troops

Political deadlock continues amid 3 months of protests and deadly police crackdowns, with demonstrators railing against corruption and Iranian influence

Grand Ayatollah Ali al-Sistani calls killing of 16-year-old a 'horrific crime,' also denounces recent attacks on anti-government protesters

Adel Abdel-Mahdi says he will ask parliament to allow him to step down after sermon by country's top Shiite cleric calling for lawmakers to withdraw their support

Not immediately clear whether the blast targeted protesters; top cleric warns government to heed calls for reform, calls for new election law