The Border Force commissioner, Roman Quaedvlieg, has been dismissed from his post on the grounds of misbehaviour.

After being on leave with full pay since May last year while his case was investigated, he was sacked on Thursday by the governor-general in council on the recommendation of the government. Malcolm Turnbull had Attorney-General Christian Porter review the outcome of the investigation and advise the government.

Quaedvlieg’s offences were intervening to help his partner pursue a job with the Australian Border Force (ABF), and failing to disclose his relationship with her.

He acted “to modify policies relevant to recruitment processes so as to advantage … a particular candidate for ABF employment”, Home Affairs Minister Peter Dutton said in a statement tabled in parliament.

He “engaged in acts, and made omissions, which materially advantaged that candidate over other comparable candidates”.

He also “engaged in misbehaviour” by failing to disclose his relationship “and by making a wilfully or recklessly false statement to the minister for immigration and border protection in relation to the status of his personal relationships”.

The statement said Quaedvlieg has “provided long and conspicuous public service in the critically important areas of law enforcement and national security. However, the relevant conduct went beyond an isolated error of judgement and ultimately undermined his capacity to continue in the office of ABF commissioner.”

After the tabling, Quaedvlieg – who was on an annual salary of about A$620,000 – repeated earlier denials of the accusations against him.

He said he had been given a short opportunity to resign before the termination. “However I chose not to do that as it is tantamount to a concession of culpability, which I strenuously deny.”

He has made criticisms in the past of the extended investigation process, which involved two inquiries, and said on Thursday he intended “to pursue these more formally in the relevant forums”.

“I will now take some time to fully consider my options.”

Speaking before the announcement, Dutton told 2GB he felt for Quaedvlieg and his partner, and for his ex-wife and children.

“It’s not an easy situation and it’s not something that deserves to be across the front pages of the paper so I just don’t have any public comment to make in relation to it,” Dutton said.