Thieves have targeted poker machines and tills during more than a dozen overnight burglaries and armed offenders have twice stormed Canberra clubs during operating hours.

A man armed with a sawn-off shot gun threatened the duty manager at The Mawson Club before he grabbed cash and fled in the early hours of Saturday.

The worker handed over the cash and the robber ran away.

Mr House said the attack was disturbing and had been witnessed by club patrons and staff, who were offered counselling.

"Particularly where weapons are involved it's quite terrifying for staff.

"Anyone who's had a weapon pointed at them as part of a robbery, it can be a life-changing experience.

"It's not to be glossed over at all, it's to be taken very seriously."

In a separate incident, three armed men stormed the Rugby Union Club in Turner and made staff lie on the floor and open a safe before they fled with cash on May 31.

Mr House said it was unusual to see so many incidents so close together.

"I haven't seen a spate of 12 or so in the space of two or three weeks before, I don't think anyone has."

ACT Policing will hold a seminar for club employees this week to discuss security and safety measures for staff in the wake of the attacks.

"We'll continue to work with police on information sharing and help in any way we can but I'm certainly keen for some arrests sooner rather than later," Mr House said.

He said CCTV was installed at the venues but staff were working with police on further "target hardening" measures to boost safety and security.

"A lot of them have tended to be unsophisticated attempts at getting money and in a lot of cases staff have witnessed suspicious behaviour at venues before the incidents."

Police are investigating the incidents and urged anyone with information to report it anonymously to Crime Stoppers on 1800 333 000, or via act.crimestoppers.com.au.