Queensland’s deputy premier has questioned the state’s declaration rules, after he failed to list his interest in a Cairns house he helped his son buy.

The Queensland opposition is demanding to know what checks the government is carrying out on its members after the deputy premier failed to declare an interest in a Cairns property.

Jeff Seeney has updated his parliamentary register of interests after it was revealed his joint-ownership of the four-bedroom home, with his son, had not been declared.

Deputy opposition leader Tim Mulherin says it’s an extraordinary mistake by one of the most experienced politicians in the parliament.

He says the government must reveal what it has done to ensure members are complying with declaration rules aimed at warding off corruption and conflicts of interest.

“It just astounds me. This is a guy that’s been in parliament since 1998 – 16 years. He should have known better,” Mr Mulherin told the ABC.

“His name is on the title, it’s on the mortgage. Under pecuniary interest rules it should have been declared.

“We want to know how many random audits has the government carried out on itself?”

Mr Seeney has said he did not stand to gain financially in any way from the house, and was only the guarantor on the loan.

“For approval of the loan, the bank insisted that my name be included on the property title,” he wrote in a letter to the clerk of parliament.

“I have zero equity in the property. I receive no income from the property and have no share in any capital gain from the property in the future.”

His letter asked the clerk to update his register of interests, but also questioned whether such arrangements should have to be declared.

“This issue enlivens the question of whether a legal interest that is a zero financial interest, such as a loan guarantee or Enduring Power of Attorney, is a declarable interest to parliament,” he wrote to the clerk.

“I seek your consideration and subsequent advice to this question as I would think such arrangements are not uncommon and may well affect a number of members.”