The mystery over the pen comes a year after Mr O'Farrell was forced to resign the premiership after failing to declare his receipt of a $3000 bottle of 1959 Grange Hermitage wine. He blamed that failure on a "massive memory fail".

The latest gift was revealed in the expense accounts of construction giant Thiess, which recorded the gift of a Mont Blanc Solitaire ball point pen to Mr O'Farrell.

The revelations about the O'Farrell gift come after Fairfax Media revealed on Monday how Thiess chief executive Bruce Munro is wanted by Indian police for questioning over an alleged fraud against one of the company's former Indian business partners.

A legal source said an internal Thiess review of political gifts, sponsorship and other expenditure had identified the luxury pen as a gift for Mr O'Farrell. The date of its purchase is unknown, but the legal source said the internal review identified other Thiess gifts and sponsorships covering the 2012 and 2013 calendar years.

The review also identified a series of other purchases by Thiess staff that broke company policy banning gifts to officials and the use of company credit cards on personal expenses.

In 2013, Thiess was part of a consortium which won a $1.15 billion NSW government contract to dig the rail tunnels for Sydney's North West Rail Link.

The former premier's register of pecuniary interests makes no mention of a gift from Thiess. Gifts valued at more than $500 have to be declared on the NSW parliamentary register and on the ministerial declaration of interests.

In a statement to Fairfax Media on Monday, Mr O'Farrell said: "A search of my premier's diary shows the only time I met any representative of Thiess, including Bruce Munro, was on 25 June 2013 at an event for the North West Rail Link project.

"Having checked with the minister for transport and my staff who attended the event, none of us recall a Mont Blanc pen being presented to me.

"If such a gift had arrived separately in my office, it would have been dealt with by my staff in accordance with the ministerial and parliamentary guidelines.

"A search of the Premier's Department register of official gifts does reveal a Mont Blanc pen was declared in 2013/14 after it was presented to me at a meeting with an education group. I am advised the pen is still in the possession of the department."

The legal source said Thiess was advised to investigate whether the purchase of the pen for Mr O'Farrell breached the company's policy which bans gifts to government officials.

Mr O'Farrell famously resigned last year, citing a  " a massive memory fail", after telling the NSW Independent Commission Against Corruption that he had not received a $3000 bottle of Penfolds 1959 Grange from Liberal donor and Australian Water Holdings boss Nick Di Girolamo.

A day after telling ICAC, "if I received a bottle of 1959 Penfolds, I do think I'd know about it", Geoffrey Watson, the counsel assisting the ICAC commissioner, unleashed a barrage of documentary evidence to show the wine had been received, producing a handwritten note of thanks from Mr O'Farrell to Mr Di Girolamo.

Mr O'Farrell was grilled by Labor MP Luke Foley in 2013 when he appeared before a NSW Parliamentary committee about his government's relationship with a lobbyist employed by Thiess, Joseph Tannous, who was also a member of the state Liberal Party's executive committee.

Fairfax Media is not suggesting Mr Tannous had any role in the purchase of a pen for Mr O'Farrell.

Thiess's review also found other gifts to politicians, including $2500 worth of limousine hire for Ipswich's Mayor Paul Pisasale at the 2012 and 2013 Melbourne Cups.

Mr Pisasale has disclosed the Thiess hospitality as required on his council's register.

Clarification: An earlier version of this story said Paul Pissale was a member of the Liberal National Party. This is not the case.