Asia-Pacific leaders gather in Russia's far east this weekend for talks aimed at promoting trade but territorial disputes and other regional tensions may cloud the event.

The annual Asia-Pacific Economic Cooperation (APEC) summit aims to tear down trade barriers and promote integration across 21 economies covering the Pacific Rim, stretching from China to Chile.

But this year's meeting, in the former military port city of Vladivostok, will take place as tensions have reignited between APEC members Japan, South Korea and China over decades-long territorial disputes.

China has also become locked in hostile rows with APEC members Vietnam and the Philippines over competing claims in the South China Sea.

Meanwhile, China has been showing increasing annoyance with what it perceives as American efforts to contain its global rise, which it said were highlighted by US Secretary of State Hillary Clinton's latest sweeping tour of the region.

The disharmony could affect progress on trade at the leaders' summit on Saturday and Sunday, analysts said, although they believe everyone involved will work hard to ensure the summit's agenda is pushed forward.

"(The tensions) will probably make the formal meetings a little bit less friendly and warm than they might otherwise have been," Deborah K. Elms, head of the Temasek Foundation Centre for Trade & Negotiations at the Nanyang Technological University in Singapore, told AFP.

"But I don't think that any country wants the current problems in territory to spill over into economics at this point -- and certainly derail the limited APEC agenda."

Among the key figures at the summit will be Clinton, Russian President Vladimir Putin, Chinese President Hu Jintao and Japan Prime Minister Yoshihiko Noda.

Clinton is representing President Barack Obama, who cannot attend because he is campaigning for re-election.

World leaders are known to veer away from the formal agenda at APEC summits to discuss pressing issues, especially on the sidelines when they take the opportunity for face-to-face meetings.

"Leaders being leaders, they are free to talk among themselves as to what topics they feel are important and relevant," APEC executive director Muhamad Noor told AFP.

But Noor said the Vladivostok meeting's formal talks would focus on speeding up trade liberalisation -- including cutting tariffs on environmentally friendly products -- and ensuring steady food production to stop steep price rises.

Officials would also likely discuss ways to minimise the impact of disasters on the global supply chain, he added, noting industrial disruptions caused by last year's earthquake and tsunami in Japan and floods in Thailand.

Noor said average tariffs across APEC members were under 6.0 percent, down from 17 percent in 1989, when the group was formed, and officials were now focused on toppling non-tariff barriers.

APEC members account for 44 percent of global trade and about 41 percent of the world's population.

Last year's summit in Hawaii was dominated by Obama's push for an Asia-Pacific free-trade area called the Trans-Pacific Partnership (TPP).

Some progress has been made on the TPP since, with the number of countries officially involved in the talks now up to 11.

It is not on the formal agenda this year, with Russia not involved, but discussions among participants will be held on the sidelines.

Russia has spent $20 billion in recent years upgrading Vladivostok -- a former naval capital that fell into disrepair after the fall of the Soviet Union -- building bridges, highways, an airport terminal and a rail link.

The event is being held at new university facilities on Russky Island, just outside Vladivostok, with Putin hoping the gathering will showcase Russia's ambitions to be a major Pacific player.

However, the revival efforts for Vladivostok have been beset by problems including cost overruns, shoddy construction and criticism about bad planning.

Putin is scheduled to deliver a speech in Vladivostok during which he is expected to highlight Russia's increasing presence in the region.