A demonstration threatens to shut down roads into the West Qurna 1 oil field as protesters, emboldened by a supportive message from Sistani, rail against government failures.
A shut-down of transmission lines left millions without power for hours, reinforcing the grievances of a protest movement that has caused minor disruptions at oil sites.
Attacks on Basra oil field and power lines mean promises of jobs and services have yet to settle concerns.
Widespread civil unrest has begun to subside, at least temporarily - leaving key oil sites disrupted but intact.
Demonstrators turned violent on fifth straight day of protests in an attempt to enter Basra oil fields, though were repelled by security forces.
Unknown assailants alleged to be the self-proclaimed Islamic State killed workers at a pipeline warehouse in Dibis, northwest of Kirkuk.
Iraqi authorities have discovered several small-scale smuggling rackets in and around Basra over the past year.
Iraqi security forces shot protesters in an escalation of chronic frustration with a lack of jobs and services, including salty water that shut down the Basra refinery.
Federal oil exports increased, but the oil price pushed down earnings, and Kurdistan tanker loadings slowed due to outages.
Kurdistan scolded for late response to court, as both it and federal government instructed to present additional legal arguments.
