A senior Liberal Party official attended last night's dinner with Cabinet minister Malcolm Turnbull, the Treasury secretary Martin Parkinson, and latecomer Clive Palmer.

The ABC has been told the Liberal Party's federal vice president Tom Harley was at the dinner, which Mr Palmer is describing as "chopstick diplomacy" amongst "friends".

Mr Harley is also the chairman of the conservative think-tank Menzies Research Centre, which is affiliated to the Liberal Party.

Mr Harley's colleague, businessman John Fast, was also at the dinner. Their company Dragoman describes itself as a "risk advisory" firm, and not a lobbying firm.

Mr Harley was in Canberra to attend the Minerals Council event at Parliament House, at which Prime Minister Tony Abbott said the Government had taken "significant risks" with its budget.

The dinner involving the four is being described as a "chance" meet-up, with Mr Turnbull and Mr Harley meeting Dr Parkinson in the Parliament House carpark and inviting him along to dinner.

Mr Palmer, who arrived later, said it was the first time he had met Dr Parkinson. In a statement, a spokesperson for Treasury said the secretary was "not aware" Mr Palmer had been invited.

A statement issued by the Treasury department this morning said: "The Secretary openly attended a personal dinner with Mr Turnbull and colleagues last night. He was not aware Mr Palmer was going to be at the restaurant and, indeed, Mr Palmer did not arrive until after the dinner had commenced. The Secretary makes his own decisions about what invitations he accepts."

A Treasury spokesperson added that Dr Parkinson has known Mr Harley for a number of years and was having dinner with him in his role as a prominent businessman. Dr Parkinson was not in the habit of enquiring about people's political views, the spokesperson added.

The dinner made headlines when Mr Palmer and Mr Turnbull were photographed leaving the Wild Duck restaurant in the waterfront Canberra suburb of Kingston.

Mr Palmer, whose Palmer United Party will share the balance of power in the Senate from July, is refusing to negotiate with the Federal Government about passing or blocking legislation until he gets more parliamentary staff.

He said last night's dinner was not "official business", but said he did raise his concerns about the budget's impact on pensioners.

Mr Palmer says he is still planning to oppose key measures in the budget, which he has called "a rape on the Australian community".

"It's a betrayal of every principle that Robert Menzies stood for when he founded the Liberal Party, that Malcolm Fraser fought for in the 1980s, that John Howard took to all the elections," he said.

Asked if these concerns were raised at the dinner, Mr Palmer said the conversation was more personal.

"It wasn't an official discussion, I will say during the week we had a number of official discussions which we cancelled and we didn't proceed with," he said.

"Otherwise we just talked about our children, about the fried rice, there was some discussion about the duck, a little bit about the chicken, that’s about all."

Mr Palmer says he did not invite Mr Parkinson and did not know he would be there when he accepted Mr Turnbull's invitation to dinner.

"I didn't invite Martin there, I was invited by Malcolm, Malcolm sent me a text and suggested I should call in and have a bite of Chinese after the Minerals Council [dinner.]"

He said he arrived late and Dr Parkinson and Mr Turnbull were already eating and drinking.

Asked if he considered the attendance of a senior public servant at the dinner appropriate, Mr Palmer said he was too focused on his food to consider the matter.

“When you're concentrating on some Peking Duck and looking forward with great anticipation to a banana split at the end of the night, you've got to say, what are your priorities?

"Certainly your priority is not to take any consideration for a public servant. They tend to be boring, public servants.

"He was quite a nice chap; he had a lovely smile, a pleasant disposition."

Mr Palmer said he was open to being "buttered up" with "free meals" but said the Liberal leadership was not discussed and only mentioned in passing.

"The only thing about leader that was discussed was that Malcolm ... once was a leader of the party.

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"I think the Liberals have moved on from that."

Mr Palmer then proceeded to mock the man who replaced Mr Turnbull as the leader after a bitter stoush over carbon pricing.

"They’ve got a charismatic leader in Tony Abbott that can instil in the nation a vision for the future, that can have a fluid discussion with the Australian people, that can listen to what the people want. With a leader like that, what more could you [want?]" he asked.

As for who picked up the bill, Mr Palmer says he does not know, but it definitely wasn't him.

"I always like a free meal," he told reporters.

"I can't remember who paid the bill but I just know I didn't, that was the most important thing for me, being as greedy as I am, getting that last cent was very important to me."

Treasurer Joe Hockey has been asked whether he sanctioned his Cabinet colleague to have dinner with his departmental secretary and the Palmer United Party leader.

"Well I'm sure it was a coincidence, Canberra's a small place on a Wednesday night," he said.

"Clive's said he didn't want to meet with us so I'm sure he bumped into Malcolm - that's part and parcel of Canberra," said Mr Hockey.

He said he had not had any meetings with Mr Palmer himself.

Opposition Leader Bill Shorten says the dinner leaves Mr Hockey looking like a "goose."

"Malcolm Turnbull was eating Peking Duck last night, Joe Hockey is left looking like a goose this morning, and we've got a lame duck budget with a lame duck Treasurer," he said.

"Joe Hockey didn't even know what Martin Parkinson was doing there last night. Joe Hockey was left looking like a goose, he doesn't even know what his other ministers and Treasury secretary [are] doing."