Pacific nation ministers and negotiators are scrambling to lock in a major Pacific trade deal, as talks come to a head in the US city of Atlanta.

Negotiations over the 12-country Trans-Pacific Partnership, which would cover 40 per cent of the global economy, are continuing into another night after five days of marathon talks.

A ministerial press conference to announce a deal was originally scheduled for Monday morning, Australian time, as reports emerged of a deal between Australia and the United States on intellectual property rules for new-generation medicines.

But that press conference is now expected late Monday night Australian time, as talks drag on.

Earlier, Australian Trade Minister Andrew Robb told reporters on the ground that so-called "biologics" remain a live issue in the negotiations.

Australia's refusal to concede ground to the US on the issue has held up talks for days.

In an earlier statement, Minister Robb said there is 50 per cent chance the Trans-Pacific Partnership trade deal would be agreed today.

Key points: A resolution to the lingering 12-nation TPP agreement expected today

Data exclusivity broadly means the time period companies have before they are forced to release information about how to make new medicines.

Once that information is released, it can be used by other companies to make cheaper generic versions of the drug.

The United States allows pharmaceutical companies an exclusive period of 12 years to use clinical data behind the approval for a new biological drug, and were pushing for that in the TPP.

Mr Robb will not move further than five years, despite the US pushing for a compromise eight year period.

"Australia's current arrangements ... are completely adequate and any proposed changes are non-negotiable, this is a red line issue for us," he said.

It is claimed any extension of the data provisions could hit the health budget, but other countries at the negotiating table have expressed concerns at the delay.

Japan's economic minister Akira Amari warned it could be the "last chance" of getting a deal.

The ABC understands progress has been made on market access for industries like beef, horticulture, wine, seafood, grains but negotiations over dairy and sugar remain unresolved.

New Zealand and the US are understood to be locked in talks over opening up the American market to more imported dairy products.

But Australian Agriculture Minister Barnaby Joyce told the ABC that "the negotiations are pretty well finalised" from the perspective of Australian agriculture, although he said he will leave it to Mr Robb to announce the details.

Joyce confident TPP deal to be finalised during Atlanta talks

Australia's sugar industry is adamant the TPP must deliver better access to the US market, while the dairy industry wants better access to the US, Canada and Japan.

Mr Joyce said Mr Robb called him at 4:00am on Monday to discuss the deal.

"I think we'll find, like with most of these things, is that some areas we're very happy about and then others where people will say, 'I could have been happier, I could have got more'," Mr Joyce said.

"In any deal you don't get everything you want, there is nothing in life where you get everything you want, and you get to a point where you say yes or no, and you pick the deal up or you turn it down.

"We turned down the first one because we didn't get as much as we wanted.

"My view this time, is that we'll probably pick it up."

Asked if he was therefore confident a deal would be finalised in Atlanta, Mr Joyce said he's "a confident guy".

"I backed the North Queensland Cowboys in the game last night, I was confident right to the end," he said.

When asked about the impasse over biologics, the Minister for International Development and the Pacific, Steve Ciobo said: "We are not going to jeopardise Australia's national interest. We are not going to put Australia's national interest in terms of access to affordable medicines at risk."

"So, that was our starting point going into negotiations," he said.

However, he said, the TPP would be "great" for Australians in the long-run.

"It's giving Australia great market access to 40 per cent of global GDP."

The Obama administration had previously proposed lowering the threshold to seven years, but has pushed a proposal for an eight-year minimum in the TPP talks.

Australia — along with others such as New Zealand and Chile — has been unwilling to offer more than five years protection for the medicines, because longer terms would increase the cost of state-subsidised medical programs.

Drug companies argue a longer period is needed to create an incentive for developing treatments for diseases such as cancer and arthritis

The Obama administration has been the prime driver behind the TPP, to create a foundation for "21st century trade rules," setting standards on trade, investment, data flows and intellectual property that eventually non-TPP members — particularly China — will have to accept.

ABC/wires