"Whether we label the (U.S. President Donald) Trump administration as protectionist, it is clear that they take a radically different approach towards trade", Lee was quoted as saying. The region is NSW's second largest trading partner, with $19.1 billion worth of goods moving each year between NSW and ASEAN countries.
Ahead of the meeting, however, the Australian and Singapore leaders stuck to economic topics in their remarks.
Leaders of ASEAN and Australia will adopt a Sydney Statement, a joint declaration of the summit and a Memorandum of Understanding (MoU) on anti-terrorism co-operation between ASEAN and the Australian government.
"We must face the world, not turn from it. Embrace free trade, not retreat from it, and do so on the basis of strong and transparent rules, fair and open competition, and non-discriminatory legislation".
He said Singapore had been directly affected by the US trade measures.
Four Asean countries-Brunei, Malaysia, Singapore and Vietnam-are among the 11 who have signed up to the TPP.
Protectionism is a "dead end", Australian Prime Minister Malcolm Turnbull said yesterday, when he and Singapore Prime Minister Lee Hsien Loong made a strong push for countries to continue working together on free trade. Australia is not a member of the regional grouping, but is hosting the special ASEAN summit, which, analysts said, reflects the country's intention to deepen economic and political ties in Southeast Asia in the face of rising Chinese influence and declining United States interest.
"The human rights crisis in Rakhine state and Myanmar as a whole must be on top of the agenda this weekend in Sydney", said James Gomez, AI's director for Southeast Asia and the Pacific.
Officially, the summit will focus on fostering closer economic ties among the 10 members of ASEAN and Australia, and countering the threat of Islamist militants returning to the region from the Middle East. The New York-based rights group wants human rights on the agenda in Sydney.
Suu Kyi, a Nobel Peace laureate, has been vehemently condemned by human rights activists for failing to take action amid a military crackdown on her country's minority Rohingya Muslims.
Hun Sen, Cambodia's long-serving leader who had a court dissolve the main opposition party previous year, has threatened to hunt down and beat anyone who demonstrates against him in Sydney.
Another controversial figure, Philippines President Rodrigo Duterte, whose crackdown on illegal drugs has led to thousands of deaths, is expected to stay away from the summit as the only leader of the 10 ASEAN member nations not to attend.
Major ASEAN states such as Indonesia are likely to use the forum to push for Australia to be invited to apply for full membership in the organisation.
Turnbull told reporters he would discuss the Rohingya with Suu Kyi when they meet.
In one such move, Mr Turnbull said, Asean and Australia will team up on a new Digital Standards Cooperation Initiative - a set of standards to make it easier for businesses to conduct cross-border digital trade.