Labor is facing claims of being a soft target for unions after industrial unrest in WA rocketed to its highest level since the last time the party was in power in the State.

Australian Bureau of Statistics figures show 33,600 working days were lost during the three months to September 30 as workers went on strike at a number of sites.

Chief among them were the mining, refining and port operations of aluminium giant Alcoa, which was hit with rolling strikes after 1600 employees protested against a proposed pay deal.

Bus drivers employed by Transperth contractor Transdev were also among those believed to have walked off the job during the period as they pushed for higher wages.

It was the highest incidence of industrial dispute since the December quarter of 2003, when striking workers caused 41,000 working days to be lost during the first term of the Gallop Labor government.

The State Opposition seized on the figures, arguing they showed Labor was incapable of keeping unions in line.

Industrial Relations Minister Bill Johnston dismissed the claims as “ridiculous”, saying most strikes involved workers covered by Federal workplace laws, which were administered by the Morrison Government.

Mr Johnston said though it was concerning relations had deteriorated to the point workers “felt the need” to strike, the State Government could not be held accountable for action taken under the Federal system.

“We would always prefer that workers and employers can work together to solve their problems,” he said.

Shadow industrial relations minister Peter Katsambanis said the State Government had to take some of the blame for the increase, saying some of its ministers had even encouraged industrial action.

“Strike action has ballooned under the McGowan Labor Government and this wake-up call highlights the dangers of WA Labor on business and the economy,” he said.

“The Premier is obliged to repay the unions that campaigned heavily to get him into government and that support has been repaid by encouraging strike action on Western Australian worksites, including the Premier and ministers standing front and centre on picket lines.”