Iraq's top Shiite cleric said on Friday he would no longer deliver regular weekly sermons about political affairs, which for years have been a source of guidance for Iraqi politicians and his millions of followers.Grand Ayatollah Ali al-Sistani did not give a reason for suspending the sermons, which have lately focused on the government's battle against DAESH militants and anti-corruption efforts. "It has been decided not to continue this on a weekly basis at the present time, but only as demanded by events", Sistani's aide Ahmed al-Safi, who delivered the message, said in a televised speech from the southern shrine city of Kerbala before reciting a prayer. Sistani, a reclusive octogenarian, enjoys almost mythical status among millions of Shiite followers and wields authority that few Iraqi politicians would openly challenge. His political sermons have ranged over issues such as security, elections and the economy.He called in June 2014 for Iraqis to take up arms against DAESH after they seized nearly a third of the country's north and west. Tens of thousands of Shiites heeded the call. Sistani then endorsed the sidelining of former Prime Minister Nuri al-Maliki.A spokesman for Sistani's office was not immediately available to comment on the decision. A sermon two weeks ago expressed frustration at inaction in solving Iraq's myriad security, political and economic challenges.