Federal Liberal MP John Alexander has resigned after saying he “cannot be certain” he is not a dual citizen.

Mr Alexander’s father was born in Britain and never renounced his citizenship, meaning the MP is likely a dual-British citizen by descent.

He will become the second Lower House Coalition MP to resign over the citizenship debacle.

“I have always believed that I am Australian and solely Australian,” Mr Alexander said at a press conference.

“In view of recent events and the High Court decision, in my position, I have had to thoroughly examine my situation.

“Given what I have learned about the constitution and understanding now of the High Court decision just a couple of weeks ago, I can no longer, with sufficient certainty, maintain the belief that I have held through my 66 years.

“Therefore, it is my obligation that I must resign. That’s what I will do.”

The Member for Bennelong was born in 1951, two years after the creation of Australian citizenship in 1949, and says he intends to contest a by-eleciton in his seat.

“I think there is a great need for certainty, to clarify the situation and to do so as expeditiously as possible,” he said.

“I will seek the support of my party to contest the by-election for Bennelong.”

Alexander concedes he is ‘most likely’ a dual citizen

While Mr Alexander admitted there is still confusion as to whether he does hold dual-British citizenship, he said there was enough to doubt to force his resignation.

“It is not absolutely conclusive, but the probability of evidence is that I most likely am (a dual citizen),” he said.

“I think I simply got to the point I couldn’t hold the belief with the level of certainty that I think I needed to have.”

Mr Alexander also said he was encouraged to make a swift decision by Prime Minister Malcolm Turnbull.

“I spoke to the Prime Minister late yesterday. I told him of my intentions,” Mr Alexander said.

“He encouraged me to be decisive, to act expeditiously, and to put things beyond any question of doubt, and that’s what I think the people of Bennelong want, and Australia is tired of this absurd situation.”

Mr Turnbull was informed of Mr Alexander’s situation on Monday, at which point the Sydney-based MP began contacting British authorities for clarification.

The ongoing citizenship scandal can now add Mr Alexander to a list of victims that also includes former deputy prime minister Barnaby Joyce and senators Fiona Nash, Scott Ludlam, Larissa Waters and Malcolm Roberts, who were all found to have breached that section of the constitution.

– ABC