A spokesperson for Alberta Premier Jason Kenney is dismissing complaints that he disrespected the legislature and public sector workers by handing out earplugs to his caucus during a debate on Bill 9 late Wednesday night.

"This was a harmless and light-hearted attempt to boost government caucus morale after being forced to listen to the NDP's insults, lies and over-the-top rhetoric for hours on end," Kenney's press secretary Christine Myatt said in a written statement Thursday.

Government House leader Jason Nixon echoed that statement saying UCP MLAs were just joking around during a late night debate.

"Certainly nobody was wearing earplugs during debate inside the legislature, that's a ludicrous assessment," Nixon told reporters.

"Caucus having humorous moments together does not lower decorum in the house."

Bill 9 delays wage reopener talks for 180,000 nurses, teachers and government workers until the end of October. The NDP Official Opposition and labour leaders call the legislation an illegal attack on workers' rights.

Edmonton-South NDP MLA Thomas Dang watched from across the aisle as Kenney handed out earplugs to his MLAs.

"I heard him say 'this is so you don't have to listen to Thomas and the others over there,' " Dang said. "And I think that's something that is truly disappointing and unbecoming of a premier."

Labour leaders also weren't amused by the earplug stunt.

"What the UCP did last night was outrageous and insulting," Gil McGowan, president of the Alberta Federation of Labour, said in a news release.

"They showed disrespect and contempt for both Alberta workers and the democratic process. And the bill they passed is illegal."

Bill 9 passed third and final reading just before 7 a.m. Thursday after an all-night session. The Alberta Union of Provincial Employees plans to challenge the bill in court.

The first reference to earplugs came just before 11:30 p.m. when Edmonton-North West NDP MLA David Eggen remarked on them as he spoke in favour of an NDP amendment to the bill which was later defeated.

"I would beg an answer from the members opposite, although I can see that many of them are wearing bright pink earplugs that their premier is handing out to all of them right now," Eggen told the legislature.

"Probably many of them can't hear what I'm saying right now."

Kenney could be seen walking around in the background as the speaker prior to Eggen, Cardston-Siksika UCP MLA Joseph Schow, was addressing the legislature.