Ms Watson attacked Mr Ward - who was overseas for a friend's wedding - for missing Thursday night's vote, using a media release to say the Liberal MP's "endless attempts to politicise the Albion Park Rail bypass had embarrassingly backfired".

"This is the politician who has stood up every day since the election to demand that Illawarra Labor MPs vote in favour of the government's so-called mandate to privatise electricity," Ms Watson said.

"Yet he couldn't be bothered to turn up to vote for it himself in the Legislative Assembly.

"This is the bill the government is relying on to fund $350 million towards the construction of the Albion Park Rail bypass."

Mr Ward, who is parliamentary secretary for the Illawarra and South Coast, said Ms Watson was playing "grubby games".

"For an ex-union official to attack someone for taking approved personal leave is probably the most disgusting act from a woman who is regarded on both sides as the most politically opportunistic and personally vindictive member of the NSW Parliament," Mr Ward said.

"I am a strong supporter of the leasing of 49 per cent of poles and wires to pay for the Albion Park Rail bypass - projects that Anna Watson has continually voted against. I'll pit my work ethic and the things I've delivered for my electorate against Anna Watson's work ethic and her lack of delivery to her electorate any day of the week."

Electricity network-related bills have been before Parliament since Tuesday and Mr Ward said he wasn't aware the vote would happen on Thursday.

"You don't take leave on the basis of when votes might come up," he said.

Government whip Christopher Patterson and opposition whip Noreen Hay confirmed Mr Ward's absence from Thursday's sitting was by the book.

"Gareth was not in the house yesterday [Thursday] with approved leave from myself and I'm the only one that can do that," Mr Patterson told the Mercury.

Ms Hay said: "I was advised that he was on approved leave and he was notifying me as a courtesy, as the opposition whip, which I appreciated.

"MPs work invariably seven days a week. From time to time members of Parliament have applied for, and been granted, leave and once it's approved then they're entitled to take it."

Mr Ward said Ms Watson was informed of his leave, a suggestion denied by the Labor MP.

Legislation for the 99-year lease of 49 per cent of the NSW electricity network - including 50.4 per cent of Endeavour Energy, the provider of electricity in the Illawarra - passed and will be introduced into the upper house next week.