The leaders of South Korea, China and Japan have held their first summit in more than three years, setting aside historical animosities and territorial disputes to focus on shared security and trade concerns.

No substantive breakthroughs were expected, but Sunday's meeting in the South Korean capital, Seoul, is a symbolic statement of intent by Northeast Asia's three largest economies who all stand to reap significant diplomatic and economic gains from closer cooperation.

The focus was very much on economic ties, with China - represented by Li Keqiang, the premier - especially eager to boost trade links as it seeks to inject some fresh momentum into its slowing economy.

Also high on the agenda was North Korea, whose nuclear weapons ambitions pose a worry - and threat - to all three countries, including China, which is the North's main diplomatic protector and economic benefactor.

The summit will be capped on Monday by a first ever one-on-one summit between South Korean President Park Geun-hye and Shinzo Abe, Japanese prime minister, after an extended diplomatic freeze.

South Korea and Japan together host about 80,000 US troops, the core of America's military presence in the Asia-Pacific. The US wants to solidify its alliance with the two countries to better deal with a rising China and a North Korean threat.

Exchanges resumed

Japan and China have been gradually resuming exchanges following 2012 tensions over the control of disputed islands in the East China Sea.

The rift began healing after diplomats agreed to restart contacts last November when Chinese President Xi Jinping briefly met and shook hands with Abe.

Another point of friction is Korean women forced to serve as sex slaves for Japan's Imperial Army troops, a topic that South Korea and Japan say will arise during the Abe-Park meeting.

South Korea-Japan ties still strained over 'comfort women'

In the face of protests by China and South Korea, Abe was forced to abandon his earlier plans to revise Japan's 1995 apology over its wartime aggression and an earlier apology to so-called comfort women.

Japan has apologised many times before, but many in South Korea see them as insufficient.

Park has met Xi six times since she took office in 2013 in efforts to further strengthen ties with China, South Korea's largest trade partner, which also has leverage with North Korea.

High-level contacts between Japan and its two Asian neighbours dwindled after Abe took office in late 2012.

Many in South Korea and China see Abe as trying to whitewash Japanese atrocities inflicted during its colonisation of the Korean Peninsula and invasion of China in the first half of the 20th century.

Despite protests by South Korea and China, Abe has not yielded on his nationalism. Even so, the three countries, closely linked economically, are pushing to find a way to improve ties.

"I think it's very meaningful for the leaders of the three countries have gathered at the same place," Park said at the start of Sunday's meeting, according to South Korean media pool reports posted on the website of Park's office.

"Today's summit meeting is a precious opportunity for us ... so that I hope it will be a venue for in-depth discussions."

Leaders' opinions

Abe said the three countries must bolster cooperation, saying he wants to use the summit as a chance to exchange opinions "candidly" on regional and international issues.

Li, for his part, said it was unfortunate that there were lack of understanding among some of the three countries but that China hopes the three nations can work together and invigorate the regional economy and peace.

On Saturday, Park and Li met separately and agreed to work towards ratifying by the end of the year a bilateral free trade agreement that their legislatures have yet to approve.

Park and Li met in Seoul on Saturday and agreed to work towards ratifying a bilateral free trade agreement [AP]

North Korea is also on the agenda. The country's nuclear bomb and missile programmes have long posed a serious security worry for South Korea and Japan.

China is North Korea's only major ally and biggest aid benefactor.

Park told Li that she wants China to continue to play a constructive role on North Korea issues, while Li called for more patience to continue efforts to achieve a nuclear-free Korean Peninsula, according to Park's office.

South Korea, China, Japan and North Korea are all members of now-dormant international negotiations on ending North Korea's nuclear ambitions. The other two members are the US and Russia.

Source: Al Jazeera and agencies