The TPP 11 was signed earlier in March and includes Australia and Association of Southeast Asian Nations (ASEAN) members Malaysia, Vietnam, Singapore and Brunei.

Prime Minister Malcolm Turnbull has been keen to entice Indonesia President Joko Widodo to the fold.

"We kept the train on the tracks and of course it's now open for others to join," Mr Turnbull told a business lunch at the ASEAN-Australia special summit in Sydney on Saturday, as he spoke alongside Mr Widodo.

"Indonesia perhaps in the future, Mr President."

Mr Robb who was involved in negotiations on the original TPP, which had included the US when the Obama administration was in power, participated in the ASEAN-Australia business forum.

He said based on discussions he had on a recent business trip to Jakarta it appeared some Indonesian government ministers were kicking themselves that the country hadn't gotten involved and were envious that Vietnam had.

"They're all feeding off one another," Mr Robb told AAP.

Mr Robb said he was amazed by Vietnam's commitment to such a modern 21st century trade agreement, considering their highly regulated background as a communist state.

"To see both Vietnam and Malaysia signing up to it, both those countries have much further to go in liberalising, it's a much bigger political ask," Mr Robb said.

Now that the TTP trade pact is signed, Mr Turnbull has urged leaders to get behind a "high quality" Regional Comprehensive Economic Partnership deal.

Australia, the full ASEAN bloc as well as China and India are among countries still negotiating that deal.

Singapore's Prime Minister Lee Hsien Long said there is hope the deal can be finalised this year.

"This is a historic opportunity to establish the world's largest trade bloc ," he told the leaders meeting on Sunday morning.

The deal would cover 45 per cent of the world's population and a third of global income.

Australian Associated Press