The 10-member Association of Southeast Asian Nations' meeting with Li followed recent violent confrontations at sea between China and ASEAN members Philippines and Vietnam that raised unease over China's increasingly assertive actions in the disputed waters.
Li did not mention the row in his opening speech in Laos' capital but said intensifying trade relations between Beijing and ASEAN were beneficial for the bloc.
"The global economy is still seeing a sluggish recovery, protectionism is rising and geopolitical turbulence has brought instability and uncertainty to our development," Li said on Thursday.
"An ultra large-scale market is our greatest foundation for promoting economic prosperity.
ASEAN nations have held a summit with China during their meeting in Vientiane, Laos. (AP PHOTO)
"Strengthening market co-ordination and synchronisation is an important direction for our further co-operation," he said.
China is ASEAN's No.1 trading partner and its third-largest source of foreign investment - a key reason why the bloc has been muted in its criticisms of Chinese actions in the South China Sea.
ASEAN leaders have repeatedly called only for restraint and respect for international law.
ASEAN members Vietnam, the Philippines, Malaysia and Brunei along with Taiwan have overlapping claims with China, which claims sovereignty over virtually all of the South China Sea and has become more aggressive in its attempts to enforce its claims.
ASEAN members and China have been negotiating a code of conduct to govern behaviour in the strategic waterway for years but progress has been slow.
Sticky issues include disagreements over whether the pact should be binding.
Chinese and Philippine vessels have clashed repeatedly in 2024, and Vietnam said last week that Chinese forces assaulted its fishermen in a disputed area of the sea.
Beijing has said it was defending its offshore territories.
The Philippines, a longtime US ally, has been critical of other ASEAN countries for not doing more to get China to back away.
The US has deployed navy ships and fighter jets to promote freedom of navigation and overflight in the waterway.
US Secretary of State Antony Blinken is representing President Joe Biden at the ASEAN summit. (AP PHOTO)
China has warned the US not to meddle in the disputes.
ASEAN leaders, who held a summit among themselves on Wednesday, also separately met with new Japanese Prime Minister Shigeru Ishiba and South Korean President Yoon Suk-yeol before convening an ASEAN Plus Three summit along with China.
The bloc will hold individual talks with dialogue partners Australia, Canada, India, the US and the United Nations that will culminate in an East Asia Summit of 18 nations including Russia and New Zealand on Friday.
US Secretary of State Antony Blinken arrived on Thursday in Vientiane, where he is filling in for President Joe Biden at the meetings.
Former ASEAN secretary-general Ong Keng Yong said despite challenges in addressing disputes in the South China Sea and the Myanmar civil war, ASEAN's central role in sustaining relative peace and progress in the region was undisputable.
"Big powers cannot do what they wish in the region," Ong said.
After the Myanmar army ousted an elected government in 2021, fighting there has descended into a civil war that has killed nearly 6000 people and displaced more than three million.
The military has backtracked on an ASEAN peace plan it agreed to in late 2021 and fighting has continued with pro-democracy guerillas and ethnic rebels.
Myanmar's top generals have been shut out of ASEAN summits since the coup.
Thailand will host an informal ASEAN ministerial-level consultation on Myanmar in mid-December as frustration grows in the bloc over the prolonged conflict.
