Prime Minister Scott Morrison has been urged by Labor to take allegations seriously that a Liberal MP may have breached Section 44 of the Constitution, after he said the issue didn't concern him.

Reports emerged on Friday that Victorian MP Chris Crewther recently became one of 14 shareholders in the Commonwealth-supported Mornington pharmaceuticals company Gretals Australia.

The opposition believes the recent investment may contravene the ban on MPs having a direct or indirect pecuniary interest in any agreement with the commonwealth public service.

Mr Morrison said he's not worried about the prospect.

"I have no concerns on the matter," he told reporters in Sydney on Friday.

"These stories they come and they go, and I frankly think the Australian people are completely over all that."

But shadow attorney-general Mark Dreyfus said the disregard shows Mr Morrison isn't taking the issue as seriously as he should.

"It is arrogance in the extreme from a desperate prime minister. It is disrespect for our constitution," he told reporters in Melbourne.

"The truth is, that Mr Morrison is absolutely terrified of losing the tenuous grip that he has on power."

Mr Dreyfus wouldn't say whether Labor would work with federal parliament crossbenchers to have Mr Crewther referred to the High Court, saying Mr Morrison should shift his attitude first.

Mr Crewther told parliament on October 23 last year that he had met with the chief executive of Gretals Australia to discuss federal government funding.

"I met with the CEO of Gretals, Alistair Cumming, to discuss how they will benefit from the $50,000 grant they recently received under the government's Global Connections Fund, part of the National Innovation and Science Agenda, as well as other federal funding they've recently received," Mr Crewther told parliament.

The Victorian MP then disclosed to the lower house in September this year that he had invested $25,000 in the company.