Union officials have told a Senate inquiry in Brisbane that crews working overnight to restore power to the city after a major hailstorm were cut to a dozen men because a utility did not want to pay overtime.

But a spokesman for Energex rejected the claims as wildly inaccurate, saying the minimum number of crews on the road was 47 and workers were earning penalty rates.

Appearing at the federal Senate inquiry into the Queensland government on Friday, the Electrical Trades Union (ETU) state organiser Stuart Traill said just six crews of two men were on the road while tens of thousands of properties remained without power.

Traill said the “bean counters exercise” was a taste of things to come if power utilities were privatised under plans the Newman government will take to the state election next year.

He was part of an ETU delegation raising concerns about the closeness of private energy generator ERM Power to the Liberal National party through donations, fundraisers and political appointments leading up to privatisation becoming the agenda.

Traill told the inquiry that the Energex manager controlling the response on Thursday night told him there would be “a handful of crews”.

“The feedback that I’ve got is there was approximately six two-man crews working between 11 last night and 4.30am this morning,” he said, adding there were still 400 live power lines down at 9am.

“There were calls made over the evening last night to our members that wanted to go out and work who had not reached their fatigue levels,” he said.

“Unfortunately they weren’t called in, despite being ready, able and willing to come in to work because Energex did not want to pay overtime rates last night and again throughout today.

“So unfortunately the people of Queensland and the small business owners are still suffering as a result.”

An Energex spokesman told Guardian Australia the ETU was completely mistaken.

The spokesman said the number of crews operating was 123 at 11pm to 80 at midnight, 56 at 1am, 58 at 2am, 53 at 3am, 47 at 3.30am, 66 at 5.30am and 214 at 6am. “They’re getting overtime,” he said.

Asked by Senator Larissa Waters if Energex had given a reason, Traill replied: “It’s all part of the cost-cutting.”

“These managers are obviously concerned heading towards a state election with the threat of privatisation about their own jobs so they’ll do whatever they’re told,” he said.

“It’s madness but unfortunately this is a sign of the times for the future if the LNP [Liberal National party] get a mandate to privatise or lease the power companies.”

As of 4pm on Friday, Energex had restored two-thirds of all power lost to properties, leaving about 31,000 still without electricity, the spokesman said.

The majority should be restored by later on Friday evening, while the remainder would require partial rebuilding of the network, he said.