Peter Dutton is on medical leave and will not return to Parliament this week after detaching his biceps from the bone in a DIY mishap.

The Home Affairs minister remains under fire over his interventions in the Victorian state election including suggesting voters were too afraid to go out to dinner because of African gangs.

But it’s at home where the senior Liberal found danger on the weekend when he was – literally – mending a fence.

It’s understood he stretched out to lift a timber rail and detached his biceps from the bone. He underwent surgery on Saturday.

“Last Friday afternoon, I suffered an injury to my arm which required surgery over the weekend,” he announced on Twitter.

“I have taken medical leave from parliament this week. The AG (Christian Porter) will act for me in my absence and will continue progressing the important national security legislation which I hope Labor will support and be dealt with this sitting fortnight.”

The loss of Peter Dutton could be catastrophic for on the floor of Parliament, but it’s understood Labor will offer him a “paired” vote on medical grounds. That means a Labor MP does not vote to cover his absence.

That complicates Labor’s hopes of securing an absolute majority of 76 votes to suspend parliamentary business to debate a national anti-corruption watchdog and suggests it will have to wait until the second parliamentary sitting week.

An absolute majority still requires 76 votes, regardless of any absent MPs.

Labor has 69 votes but theoretically can pass legislation if it secures the support of all six independent cross benchers but would also require a Liberal MP to cross the floor. If it is “pairing” any votes is will require more MPs to cross the floor.

Since the election of independent Kerryn Phelps in the seat of Wentworth, the Coalition has lost its majority and needs the support of one independent cross bench MP or the Labor Party to pass laws

Mr Dutton had planned to spend the week attacking the Labor Party over failing to announce a position on laws to grant more access to the encrypted messages of terrorists and pedophiles.

Labor leader Bill Shorten signalled this morning the ALP is likely to support the measures.

“I’ll be guided by the best evidence when it comes to national security,” he said.

“The government certainly said there is a major rush to resolve these matters, they could be right, I’ll wait until the detail. But what I want to say to Australians who hear the government talk about national security, and they look at the division and chaos in Parliament – I want to reassure them when it comes to national security, Labor and Liberal are in this together.

“We’ve worked with them on 15 occasions successfully, we’ve made 300 improvements. So I just want to reassure Australians there’s a process, we’ll get it right, we’ll work together, because when it comes to keeping Australians safe we’re all in this together.”