The unexpected rebuff of the request to help get the proposal to the investment-ready stage comes despite Chinese investors showing interest in the Australia Forum to be built as part of an ambitious city-to-lake plan to revitalise the heart of Canberra.

The rejection is a blow to the territory’s business community, which combined to back the proposal to generate jobs and investment as a buffer against the heavy hit Canberra is expecting in Tuesday’s federal budget.

''I can't recall ever the business community coming together about a priority like that,'' Canberra Business Council CEO Chris Faulks said.

''I think the rejection indicates the federal government is not listening to the business community here.''

The federal budget could unveil funding for the Barton Highway duplication or an Arlington-style national war cemetery, which Prime Minister Tony Abbott has suggested could be built in the ACT to commemorate the Anzac centenary in 2015.

But ACT Chief Minister Katy Gallagher is perplexed that Mr Abbott has rejected the request for $8 million over three years for the style of private sector infrastructure project for which he specifically asked.

She is bracing for Canberra to receive a ''big hit'' in the budget but is predicting the impact will not be as bad as the federal cuts in 1996.

During a private session of the recent COAG summit, Ms Gallagher pointed out Canberra was missing out on massive spending in the Prime Minister's infrastructure program.

''I don't know whether Mr Abbott then just said it to be polite but he said a couple of times, we're working on that with the ACT,'' she said.

''He indicated to me, we'll get onto that, but that's all I've got.''

The ACT government has been working with the territory's business community to get the convention centre project to the investment ready stage.

''We put in about $1 million to get to this point and we have agreed with the business support stakeholders on a site for the convention centre,'' Ms Gallagher said.

''I've met with the Deputy Prime Minister and the Minister for Territories, I've written to the Prime Minister, I've spoken to the Prime Minister a couple of times about the project and all the signs were receptive and positive.

''Now I've got a letter saying they are not in a position to financially support it ... but will work with us on non-financial ways of progressing the project, but the reality is we've done all the non-financial things.

''This is disappointing because it wasn't big on the dollars; it didn’t ask them to fund the actual project, it just asked them to help get to the investment ready point.

''I thought that was a real opportunity for a show of good faith from the federal government because I was specifically asked to identify private sector infrastructure projects, not public sectors ones.

''They've made it pretty clear that they don't want to talk about public sector infrastructure, they see that as the ACT government's job.

''I was specifically asked to identify the top private sector project in the city and I nominated that one, with the support of all the other groups.

''That letter was pretty disappointing to receive, I have to say, and it shows just how much influence [Liberal Senator] Zed [Seselja] is having up there.''

Ms Gallagher said investors in China showed interest in the convention project when it was presented to them recently.

''If we can get it to the investment-ready stage, I have no doubt that project will fly, so now it's how do we get there if the Commonwealth is not going to help.''

The business council's Ms Faulks said 54 industry bodies and a large number of other business organisations and individuals supported the proposal for federal government investment in a convention centre, as the number one priority for Canberra.

''This is not just a building and construction priority, this is to drive industry development, growth and jobs in Canberra over the next 20 or 30 years,'' she said.

''We were not asking for a huge amount of money and [the rejection] from the Prime Minister is really disappointing.''