Airport workers staged strikes at five airports Wednesday due to continued disagreements between state-owned PT Angkasa Pura I and its labour union over salaries, pensions and health insurance.

The coordinated six-hour strikes hit Sepinggan Airport in Balikpapan, East Kalimantan; Frans-Kaisiepo Airport in Biak, Papua; Hasanuddin Airport in Makassar, South Sulawesi; Sam Ratulangi Airport in Manado, North Sulawesi; and Pattimura Airport in Ambon, Maluku.

Sepinggan Airport workers, dressed in black shirts with the words "We're on strike", started their strike at 6 a.m., disrupting airport operations until 12 p.m.

The airport, which serves 8,000 to 10,000 passengers and 120 flights daily, returned to normal after seaport security personnel was dispatched to help with runway operations.

At Frans-Kasiepo Airport, 70 workers caused several one-hour delays of flights after they went on strike from 5 a.m. to 11 a.m., head of the labour union in Biak Primus Rahangiar said.

Angkasa Pura I's board of directors in January rejected its labour union's demand for an increase in salaries, pension payments and health insurance to retirees, as stipulated by a 2006 collaborative labour agreement between the union and the board of directors.

Under the 2006 agreement, airport workers were entitled to salaries equal to those of civil servants, which currently stand at Rp 1.2 million (US$129) for the lowest posts.

"We are making less than that. The agreement also said we would get increased pension payments and health insurance, but they still haven't fulfilled that promise," labor union head Itje Yulinar said.

Labor union secretary-general Sulistyani said the union planned to carry out more strikes if its demands were not met.

"If the board of directors continues to refuse our demands, we will hold a 12-hour strike Thursday. If there is still no response from them, we'll hold a 24-hour strike Friday," she said.

Sulistyani added that workers from Aditsutjipto Airport in Yogyakarta were ready to participate in Friday's strike.

Ribka Tjiptaning, head of the House of Representatives' Commission IX overseeing citizenship, health, labor and transmigration affairs, agreed to meet with Angkasa Pura I's board of directors to negotiate the union's demands.

"If they have indeed broken their agreement with the union, then we'll give them a harsh warning," Ribka said after meeting with Sulistyani and several union members at the House.

Ribka added that all airport workers in the labour union should continue to demand their rights together and not betray each other.

Angkasa Pura I employees of Ahmad Yani Airport in Semarang, Central Java, did not take part in the strike.

"We fight for our aspirations through a more managerial approach. Our suggestions have been passed on to the directors," said Edy Cahyono, Ahmad Yani Airport labor union chief.