Today he said he was not under any obligations to provide specific details to voters about fundraisers.
"Of course we could give you absolutely every detail, down to what we ate, but we don't do that. We're under no obligation to do that and we won't be doing that," he said on TV3's Firstline this morning.
Mr Key denied he came across as 'furtive' by not offering details of the donations.
"We were asked a very specific question by your office, 'did we go to a fundraising dinner', and we gave the answer, 'yes'. I don't think we could be much clearer than that," he told the station.
"But we're not going to get into a situation where we say where we went to dinner and whether I had the chicken or the fish, we're just not going to be doing that. No other political party does, no one is required to do that."
There was "no great secret" that political parties have to raise money for elections, he said, and part of that fundraising was "lots of dinners".
"I personally don't involve myself in fundraisers, if you like, in terms of the sense of raising money. I never talk to people about money, I don't receive donations," Mr Key said.
"I wouldn't have had a clue, basically, how much he and the other guests were giving, whether it was a lot or nothing. I just go to a series of dinners.
"But that's also true of every political leader in Parliament. Everybody has to raise money [through fundraising], because the alternative is the taxpayer does."
The year after Liu made his donation, he became a political embarrassment for the Government after a Herald investigation revealed the impact of the property developer's links to the National Party.
Maurice Williamson was forced to resign as a minister when it was revealed he had called police after Liu was arrested on domestic violence charges and told them the businessman was a big investor in New Zealand.
Liu pleaded guilty to the domestic violence charges in April last year, but was in the Auckland District Court last week seeking to withdraw those admissions. He was successful and the case is likely to now head to trial.
His $25,000 donation to Botany MP Jami-Lee Ross' campaign was refunded to his lawyers shortly after last year's election.
Mr Ross told the Weekend Herald the donation was not spent on his campaign as he was given $24,000 from the National Party, which covered his expenses. The money was then refunded to Liu "because it was not used", he said.
The story so far:
•August 2013 - Prime Minister John Key and National Party MP Jami-Lee Ross have private dinner at Donghua Liu's home. Liu donates $25,000 to Mr Ross election campaign.
•December 2013 - Liu arrested on domestic violence charges.
•March 2014 - Herald reveals Maurice Williamson lobbied ministerial colleague to give Liu citizenship against official advice and Liu's $22,000 donation to National.
•May 2014 - Mr Williamson forced to resign as a minister after Herald investigation reveals he telephoned senior police officer about Liu's domestic violence charges. Prime Minister John Key said he recalled "seeing Mr Liu at various functions, including a dinner as part of a National Party fundraiser". He does not mention the private dinner was at Liu's own home.
•November 2014 - Mr Ross returns the $25,000 donation to Liu.
• February 2015 - Electoral returns reveal the $25,000 donation.
