The base camps of two oil field service providers in southern Iraq have been stormed by angry Shia protesters, raising concerns for worker safety in the lead up to a major Shia religious festival.

The protesters broke into a drilling site used by US-based Schlumberger at the Rumaila oil field, one of the largest in Iraq, on 11 November, Reuters news agency reports.

The incident was reported to have been sparked by foreign security contractors asking for flags and banners depicting Shia religious figures to be removed. Shots were fired in the resultant row with an Iraqi worker injured.

A source close to Baker Hughes, another oil field service company operating at the field, tells MEED that its offices were also stormed by protests, after rumours had spread of banners being desecrated.

Baker Hughes issued a statement on 11 November saying it had suspended operations in Iraq and was issuing force majeure notices to its customers.

According to the source, Baker Hughes will evacuate its remaining staff from the base camp by 13 November.

Iraqi Shias are preparing to commemorate the Day of Ashura on 15 November, a day of mourning that marks the martyrdom of the Prophet’s grandson at the Battle of Karbala in 680AD.