Lower house members engaged in a 23-hour debate over separate sittings in October and passed the controversial gaming bill late at night before the chamber took a break for a week.

Murchison independent MLC Ruth Forrest in the Legislative Council on Tuesday night said those who had observed the final night of debate had reported some members had been affected by alcohol.

"It appeared that some members, who were generally only returning to the chamber late at night to vote, were clearly under the influence of alcohol and could be heard saying as much," she said.

"Those members can speak for themselves around the veracity of this, but I find it abhorrent and deeply concerning."

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Ms Forrest said nobody in Parliament should be allowed to work under the influence of alcohol.

Mr Shelton said such behaviour was not the accepted practice in the House of Assembly.

"As speaker of the house, I am not aware of any basis whatsoever for these disappointing assertions and I have not received any formal or informal complaint," he said.