Gunmen have killed at least three workers at the Akkas gas field in the western Anbar province near Iraq’s border with Syria.

Two other workers were kidnapped in the attack on 1 April, according to Reuters news agency, quoting Farhan Ftaikhan, the mayor of Qaim, a nearby town. All of them had been working for an unnamed local company, which was contracted by Korea Gas Company (Kogas), the developer of the field.

Drilling is expected to start before the end of the year, Douglas Nester, the chief operating officer of Kogas Akkas said on 26 March.

According to sources close to the company, Kogas is currently evaluating bids for the construction of a central processing facility (CPF). At least five firms are in the running for the deal, which is estimated at around $250m. Contractors bidding for the deal say they do not expect any delays as a result of the attack.

The 5.6 trillion cubic feet Akkas field is being developed by a consortium of Kogas and state-owned North Oil Company. The pair hope to reach first commercial production of 100 million cubic feet a day (cf/d) by September 2015 and then to ramp up production to 400 million cd/d by 2017.

Violence is increasing in Iraq. According to AFP news agency there were 271 civilians killed in March. However, attacks on Iraq’s oil infrastructure have been limited to the bombings of pipelines and refineries, such as the Daura refinery near Baghdad in 2011.

The Najma oil field in the northern Nineva province witnessed the first major attack on upstream activities in January 2012, forcing the developer, Angola’s national oil company, Sonangol, to suspend its operations.