The WA Opposition has launched a blistering attack on Premier Mark McGowan's 2017 delegation to China and Japan after the government revealed the 10-day trip cost more than $250,000.

Mr McGowan, three state ministers and 12 bureaucrats spent $119,281 on business-class airfares, accomodation and "associated costs", $118,284 in expenses for the China leg of the trip – including $29,254 for "media coordination fees" – and a further $19,000 on expenses in Japan.

Premier Mark McGowan celebrates the 30th anniversary of the WA-Zhejiang sister-state relationship with province Communist Party Secretary Che Jun on November 10. Credit:Twitter

Liberal upper house leader Peter Collier labelled the trip a "junket" and said it was "bullshit" the government did not reveal the full cost when he first asked about it in an early-December parliamentary sitting.

"He's taken half of Perth to China for close to a quarter of a million dollars and they are carrying on about closing Moora residential college which serves a whole community," Mr Collier said.