South Korean forces have ended their mission in Iraq, joining their Japanese counterparts who also pulled out this week.

About 520 soldiers returned to South Korea on Friday, marking the end of its four-year reconstruction mission in Iraq that had about 3,600 troops at its height - the third-largest contingent after the US and Britain.

A unit was stationed in Irbil, about 354km north of capital Baghdad, focusing on rebuilding schools and roads and providing humanitarian aid, and another unit was based in Kuwait providing air support.

Won Tae Jae, a defence ministry spokesman, said the mission in Irbil also provided medical services for at least 88,805 local residents and vocational training for up to 2,299 people in fields such as car mechanics and cooking.

"All the medical facilities and training facilities as well as 36,472 articles of equipment and materials … will remain there and will continue to serve the Iraqi people," Won said.

Despite the largely humanitarian nature of the deployment, it was largely unpopular with the South Korean public.

South Korea's withdrawal comes as Japan also ended its five year mission in Iraq this week, recalling its three aircraft involved in airlift operations.

Tokyo withdrew its 600-strong force in southern Iraq in 2006 but continued air support, lifting equipment and troops.