The NSW government's contentious changes to public sector employment conditions are likely to be passed in the upper house before midnight, the opposition says.



Labor leader John Robertson said the passage of the industrial relations bill will mean more than 300,000 public government workers shall lose out on wages and conditions.



The government earlier today shut down the upper house debate on its bill after prolonged filibustering by Labor and Greens MPs.



It used a standing order, which has not been invoked since 1906, to force the bill to the committee stage.



"The premier has then gone a step further and prevented discussion on any proposed amendments - locking parliamentarians into the chamber until the bill is passed," Mr Robertson said in a statement.



The bill was likely to go through in the upper house tonight, he added.



"The government has taken these extraordinary steps to force the parliament to immediately vote on laws that will hurt 300,000 workers in NSW including nurses, teacher and firefighters," Mr Robertson said.



The bill will give the government the power to stipulate wages and conditions for public servants, and require the Industrial Relations Commission to consent to its policy.



The government argues its bill only enforces the former Labor government's own policy.



Unions, the opposition and Greens say the bill will give the government unprecedented powers to slash wages and conditions.



AAP