Asia-Pacific leaders Tuesday backed China's roadmap for a vast new free trade area rivalling US plans for the region at a summit in Beijing where Russian leader Vladimir Putin had a tense showdown with Barack Obama.

Chinese President Xi Jinping hailed endorsement of the plan as a "historic" step towards realising the Free Trade Area of the Asia-Pacific (FTAAP).

He said it reflected the "confidence and commitment of APEC members to promote the integration of the regional economy".

The 21-member Asia-Pacific Economic Cooperation forum accounts for more than 50 percent of global GDP and nearly half of world trade.

Beijing has embraced the broader FTAAP which is seen as a rival to the proposed Trans-Pacific Partnership pushed by Washington as part of its much-vaunted "pivot" to Asia but which notably excludes China.

The FTAAP is a longer-term concept for the entire region that would build on the TPP and other free-trade initiatives.

The US president has insisted he wants China "to do well" despite simmering tensions between the world's two largest economies.

"The United States welcomes the rise of a prosperous, peaceful and stable China," Obama said in a speech Monday at the APEC summit.

- Diplomatic tensions -

China has been keen to underscore its rising trade and diplomatic clout during the summit which takes place against a backdrop of growing big-power rivalries.

Ahead of the gathering, Xi promised ever-closer cooperation with Obama's combative diplomatic rival Putin, saying it was "time to gather the fruit" of their deepening ties.

Russia and China have been brought together by mutual geopolitical concerns, among them wariness of the United States.

In less friendly encounters, the Russian leader had a close-up brush with Western anger over Ukraine and the downing of Flight MH17 in meetings Tuesday with Obama and Australian Prime Minister Tony Abbott.

Obama held talks of about 15-20 minutes with Putin, according to the White House, with their conversations covering Iran, Syria and Ukraine.

Putin also met Abbott, who has publicly declared his fury at the downing of Malaysia Airlines flight MH17 over eastern Ukraine, killing 298 people including 38 Australian citizens and residents.

Using colourful Australian sporting terminology ahead of their face-to-face encounter, Abbott had pledged to "shirtfront" -- physically confront -- the Kremlin strongman over the fate of the plane.

Abbott's office underlined that evidence suggested a Russian-supplied missile from a launcher that was then returned to Russian territory was responsible, labelling it "a very serious matter".

"The leaders have robustly spoken out in favour of speeding up the investigation of the reasons for the tragedy," the Kremlin said after their meeting.

- 'We need each other' -

For its part China is embroiled in territorial and historical disputes with Japan, with relations at their lowest point in decades.

A rare meeting between Xi and Prime Minister Shinzo Abe on Monday, the first by leaders of the world's second- and third-largest economies in three years, has raised hopes of a possible thaw.

Abe stressed cooperation with Beijing after the summit, calling for the neighbours to press ahead with tentative efforts to put their deep hostility behind them.

"Japan and China, we need each other. We are in a way inseparably bound with each other," Abe told reporters. "Japan and China both have responsibility for peace and prosperity of the region and of the world."

China and Japan are closely linked economically, but political tensions have endured between Asia's two heavyweights for decades, stemming largely from lingering anger over Japan's brutal World War II invasion of its neighbour.

Washington welcomed the Xi-Abe meeting as "an opportunity to reduce the tensions between the two countries", deputy national security advisor Ben Rhodes told reporters in Beijing.

China and the United States have jousted over differing visions of Asia-Pacific trade integration while Beijing's increasing economic and military prominence has also lead to tensions.

But at the meeting Obama himself praised China for focusing attention on APEC's role in eventually achieving the FTAAP, first proposed in 2006, but also reiterated the US priority was the smaller TPP.

"The many regional initiatives will contribute to the eventual realisation," he said. "We see our engagement in the Trans-Pacific Partnership as a contribution towards that effort."

Xi hosted Obama for a private dinner Tuesday and they were to meet again on Wednesday.

Both sides say they want to manage their relationship to avoid clashes in the past that have occurred between rising and established powers.

In a sign that they can work together, the White House announced Tuesday that they had "reached an understanding" on an agreement to reduce tariffs on information technology trade.

Obama also announced in Beijing the two governments had reached a reciprocal agreement to extend visa validity periods to as long as a decade.