Quitting ... Senator Arthur Sinodinos announces he is resigning as Assistant Treasurer. Picture: Ray Strange/News Corp. Source: News Corp Australia

In a statement the NSW Senator, who had temporarily stood down as Assistant Treasurer during ICAC hearings, said his decision would take effect from close of business.

MISTAKE: Arthur Sinodinos listed as Assistant Treasurer on press release

“I have just written to the Prime Minister in those terms,” he said.

“I thank the Prime Minister for having given me the opportunity to fulfil the role of Assistant Treasurer.

“I can confirm that I have been confidentially discussing my ministerial future with the Prime Minister and Brian Loughnane, the party director, in recent weeks.”

Senator Sinodinos said he had hoped to make his decision public on Sunday, but media reports caused him to act today.

“It had ... been agreed that I would resign today via an exchange of letters with an announcement being made on Sunday.

“I am disappointed by the reports in today’s newspapers that pre-empt this.

“Speculation on such an important matter does not assist the orderly workings of government.”

The Coalition Senator said he advised Mr Abbott on Tuesday that the reports into ICAC matters, which he was called as a witness too, would be delayed until March.

“While I am extremely disappointed by this further delay, I am confident that when the reports are finally released, I will not be subject to any finding of corrupt conduct or illegality.

“The government needs a full-time Assistant Treasurer for the preparation of next year’s budget. “On that point the Prime Minister and I agree.

“The Prime Minister has advised me that I cannot resume ministerial duties until the ICAC matters are completed and reported upon.”

Senator Sinodinos thanked his “hard working ministerial staff” and Senator Mathias Cormann, who filled in in the position.

“I very much look forward to returning to the Ministry in the not too distant future and in the meantime being a strong advocate for the Abbott government and the people of New South Wales.”

Mr Abbott said he will announce the Senator’s replacement in the next few days.

Changes ... PM Tony Abbot said he accepted Arthur Sinodinos’s resignation with “deep regret”. Picture: Gary Ramage Source: News Corp Australia

“With deep regret, I have accepted the resignation of Senator Arthur Sinodinos from the ministry, the Prime Minister said in a statement.

“He has provided sterling service to the Government and to the Parliament.

“ I look forward to his future contribution to the Government and, in the meantime, am confident he will continue to be a vigorous advocate for the people of New South Wales.”

Senator Sinodinos described the decision as “mutual” with the Prime Minister.

But he expressed his disappointment the media got wind of it early.

When it was suggested someone blabbed about the impending announcement, the Senator told Sky News “that’s right”.

He said he felt “liberated” and was looking forward to speaking “more freely” on a “strong backbench”.

Senator Sinodinos admitted there are things the government could have done better during the year.

He also called for more female MPs to be promoted.