Prime Minister Scott Morrison believes Stuart Robert has acted "in accordance with the rules", even though the Assistant Treasurer still holds shares in a $70 million taxi/ride-sharing fleet business listed on the Australian Stock Exchange and facing multiple regulatory issues.

Key points: Stuart Robert cannot sell his shares in a $70m taxi/ride-share business until December

Stuart Robert cannot sell his shares in a $70m taxi/ride-share business until December The ride-share industry faces multiple regulatory issues relevant to the Treasury portfolio

The ride-share industry faces multiple regulatory issues relevant to the Treasury portfolio Ministerial Standards require ministers to remove themselves from conflicts

Mr Robert resigned as director from three entities — including a bodybuilding supplement company — and sold shares in a gold business in September as part of his return to the ministry, his office confirmed.

But he was unable to divest his stake in P2P Transport. He has to keep his shares until December under escrow arrangements.

Escrow rules are set up by companies in order to ensure early shareholders keep their money invested for a minimum period.

A spokesman for the Member for Fadden confirmed to the ABC he would be "unable to divest until the shares are released from escrow".

The Gold Coast-based MP argues no conflicts of interest arise from him keeping the shares.

His office stated that Treasurer Josh Frydenberg has responsibility for taxation policy and the Australian Competition and Consumer Commission (ACCC).

Since becoming Assistant Treasurer, Mr Robert has issued joint press releases with Mr Frydenberg about multinational tax and competition and consumer issues.

Who is P2P?

P2P Transport describes itself as one of Australia's largest fleet management businesses focused on the point-to-point passenger transport industry.

Its 2,600 vehicles include taxi, corporate and ride-share vehicles, making its success contingent upon developments in both conventional cab and new ride-sharing sectors.

Multiple regulatory issues have direct impact on the business:

The ATO — one agency in the Treasury portfolio — continues to face pressure over how it taxes ride-share businesses such as Uber.

The ATO — one agency in the Treasury portfolio — continues to face pressure over how it taxes ride-share businesses such as Uber. Black and White Cabs, a business purchased by P2P earlier this year, was one entity that secured authorisation from the ACCC — another Treasury agency — in 2016 for its ihail smartphone app.

Black and White Cabs, a business purchased by P2P earlier this year, was one entity that secured authorisation from the ACCC — another Treasury agency — in 2016 for its ihail smartphone app. Foreign ride-share companies such as Uber face ongoing pressure to pay their fair share of tax in Australia. A Treasury paper released last week noted how ride-sharing was eroding the tax base.

Mr Robert bought shares in P2P in early 2018, according to the register of interests.

It was listed on the Australian Stock Exchange in December 2017, but its share price has subsequently dropped by a third.

Mr Robert stands to benefit from any share price rise between now and when he divests.

Standards suggest arrangements to avoid conflicts

The ministerial standards require ministers to "make arrangements to avoid conflicts of interests arising from their investments".

They suggest arrangements to avoid conflicts, such as the referral of decision-making responsibilities, divestment, or creating a trust or other arrangement that satisfies the Prime Minister.

The Australian reported in late August that Mr Robert had written to Prime Minister and Cabinet secretary Martin Parkinson and Treasury secretary Phil Gaetjens for advice about how to handle his conflicts of interest.

The ABC sought clarification around any arrangements approved by the Prime Minister's office, but a spokesperson said only that "Mr Robert has disclosed his interests fully and transparently and in accordance with the rules".

Mr Robert has had a range of investments and business dealings.

When he became Assistant Minister he sold shares in Brazilian-focused mining company Orinoco Gold.

He also resigned as director of three entities.

One was RQ Supplements, a company selling vitamin supplements with the involvement of bodybuilder Rob Quatro.

Another was Cryo Australia, a company focused on cryotherapy — the use of freezing temperatures for health benefits.

An article in The West Australian discovered that even though Mr Robert disclosed to the register of interests on September 12 that he had resigned as director of Cryo Australia, documents formally removing him as director were only registered after the journalist made enquiries weeks later.

His office emphasised that it was the board's responsibility to update ASIC with the necessary documents.