The NSW premier has endured a grilling in the ICAC witness box over a $3000 bottle of Grange said to be sent by the ex-CEO of Australian Water Holdings.

It was a bottle of Penfolds Grange that then-Australian Water Holdings (AWH) boss Nick Di Girolamo paid $3000 for in 2011, but now may cost NSW Premier Barry O’Farrell far more.

Mr O’Farrell was grilled at the corruption watchdog on Tuesday over the vintage bottle of Penfolds Grange hermitage wine that was said to be delivered to his home three years ago, although he claims he never received it.

He also came under intense pressure over his contact with Mr Di Girolamo at a time when the Liberal fundraiser was lobbying for a lucrative public-private partnership for his company.

Counsel assisting Geoffrey Watson SC said there was evidence Mr Di Girolamo, who owned half of AWH, believed the government deal could bump the value of the infrastructure company by up to $275 million.

Mr Di Girolamo has told the Independent Commission Against Corruption that in late April 2011 he sent Mr O’Farrell an extravagant drop of wine – bottled in the year of the premier’s birth – to congratulate him on securing the state’s top job in 2011.

“You were trying to butter Mr O’Farrell up with gifts,” Mr Watson said on Tuesday.

“No,” Mr Di Girolamo replied.

Mr O’Farrell denies receiving the wine at all, saying he spent Easter 2011 on the Gold Coast, and even Oscar the cocker spaniel was away from the O’Farrell family home on Sydney’s north shore about the time the delivery is said to have been made.

The gift was never declared on the premier’s pecuniary interests register although MPs must disclose any gift worth $500 or more.

Mr O’Farrell continued to plead his innocence at a hastily-convened press conference held downstairs from the ICAC hearing room.

Asked by a reporter if he would resign if it is found he has misled the commission, he said: “Anyone who walks into the commission, a court of law or gives a statement to police is conscious of the need to tell the truth.”

“I’ve told the truth today.”

But Mr Di Girolamo had told the inquiry he received a thank-you call from the premier after sending the wine.

On Tuesday afternoon, Mr O’Farrell was shown a record of a 28-second telephone call from his mobile number to Mr Di Girolamo, made about 9.30pm on April 20, 2011.

“I’ve no knowledge – I don’t know about this phone call,” Mr O’Farrell told the commission.

“What I do know is if I had received a bottle of 1959 Penfolds Grange I would have known about it and I did not receive a bottle of Penfolds Grange.”

He denied that AWH’s donations to the Liberal Party prompted him to send a letter that was “broadly supportive” of the AWH public-private partnership push in September 2010.

“We can show you lots of money going into Liberal Party coffers which coincides with this letter of support. Did you know anything about that?” Mr Watson asked.

“No, the Liberal Party’s financial code requires members of parliament to be at arm’s length from fundraising,” Mr O’Farrell replied.

He said he occasionally ran into Mr Di Girolamo at Liberal Party fundraisers and Wests Tigers rugby league matches and spoke to him by telephone every month or two and believed he was an “upright” businessman.

Mr Di Girolamo will continue giving evidence on Wednesday, when the public inquiry is expected to conclude.