An almost-$1000-a-head Liberal Party fundraiser was the scene for a meeting between the Immigration Minister and property developers fighting for a multimillion-dollar contract for the new Australian Border Force headquarters.

The dinner at Canberra's exclusive Boat House by the Lake restaurant in early September was hosted by ACT Liberal senator Zed Seselja, with Immigration Minister Peter Dutton the main drawcard.

The ABC understands it was attended by at least 10 people, six of whom were developers.

It is understood that group is led by Graham Potts from Amalgamated, and Barry Morris from the Morris Property Group. The principals came together last year in a joint bid for the contract, which on market values could be worth at least $35 million per year for the next 15 years.

The tender for the office contract, bringing together immigration, customs and border protection into one location, closed in November last year.

The successful bidder has yet to be announced because of a new tender review process put in place by Finance Minister Mathias Cormann just before this year's budget.

Among other issues, it requires the Finance Department to consider "local impacts", such as the effect on businesses that rely on public servants housed in government offices.

Senator Seselja also attended the event, and has long campaigned for the Department of Immigration and Border Protection to maintain its presence in the Canberra suburb of Belconnen.

The department is currently one of Amalgamated's tenants in Belconnen.

Peter Dutton says the tender was not discussed at the meeting. ( AAP: Mick Tsikas )

The ABC contacted Amalgamated Property Group, but they declined to comment.

In a statement, Mr Dutton's office confirmed he had attended the dinner, but denied there was any discussion about the tender.

"The Minister has no decision-making role in relation to the request for tender process," a spokesperson said.

"The Department of Finance has carriage of the whole of Government accommodation process though Project Tetrus.

"In any case, the Minister did not take part in any discussions around the detail of office space for the Department of Immigration and Border Protection."

Senator Seselja's office refused to comment on the discussions at the dinner.

"The senator does not comment on private conversations," a spokesperson said.

"However, the senator's position on the Department of Immigration staying in Belconnen is well known.

"While this is a matter for the department, he is hopeful that a decision will be taken soon."