SYDNEY - US President George W. Bush and his Russian counterpart Vladimir Putin showed no sign of progress after talks here Friday to defuse tensions over US missile defence plans that have angered Moscow.

The presidents met at a hotel in Sydney ahead of a summit of Asia Pacific leaders and shortly after Putin signed a landmark deal allowing Australia to export uranium to Russia.

Visibly grim after their hour-long meeting, Putin said the talks had been "above all related to missile defence."

But neither man gave any hint of coming any nearer on Washington's plans to deploy a missile shield in Central Europe which have provoked an increasingly tense standoff between the two sides.

The Russian leader said that experts from both sides would meet again soon to inspect a Russian radar station in Azerbaijan that Moscow has proposed using as an alternative to the Central Europe sites.

"In this way we are continuing joint work in this direction," Putin said of that visit.

Moscow says the US plans to deploy elements of a missile defence shield in Poland and the Czech Republic will upset the balance of power, while Washington insists it is aimed against potential attacks from Iran or North Korea, posing no threat to Russia.

The talks, which Bush called "both cordial and constructive," also touched on Iran's nuclear programme, Russia's bid to join the World Trade Organisation and environmental issues.

Earlier in the day, Putin and host Prime Minister John Howard had sought to ease fears that planned uranium sales to Russia posed a nuclear proliferation risk.

The Australian leader Howard vowed that "any uranium that is sold to Russia will be sold under very strict safeguards."

They signed the deal before a weekend summit of the Asia Pacific Economic Cooperation (APEC) forum, where Putin, Bush and Howard will join with 18 other regional leaders, including Chinese President Hu Jintao.

Forum delegates have been struggling to hammer out a statement on climate change, with emerging nations resisting Australia's plans to set clear goals, including for them, on curbing emissions of greenhouse gases.

Australia had been touting a tough statement as a cornerstone of the Sydney summit but Foreign Minister Alexander Downer was forced to downplay hopes of agreement.

"These are very difficult negotiations," he told reporters.

"If we can get a good declaration out of this, that would be a very great achievement. But I make no predictions about how those negotiations will go. We're still working at it."

Meanwhile a series of protesters brought some light relief to proceedings, although there was a tense but brief standoff between police and demonstrators at one event.

One of the most watched was also the cheekiest -- anti-war activists making their point with a "21-bum salute," baring one posterior for every government at the summit.

Also Friday, Bush invited Southeast Asian leaders, including an official from Myanmar, to Texas despite his increasingly sharp attacks on the isolated nation's military regime.

In recent days, he has branded Myanmar's leaders as "tyrannical" and their crackdown on activists and protests over fuel price hikes as "inexcusable."

He extended the invite after a keynote address at which he pressed China to use next year's Olympic Games in Beijing to allow more democratic openness and tolerance.

He said democracy promotion, the war on terrorism, trade expansion, avian flu, and climate change would be on the agenda for the talks, which could take place at his ranch or "another location" in Texas, an aide said.

The Asia Pacific leaders are also expected to issue a statement calling for urgent action to break deadlocked World Trade Organisation talks on bringing down tariffs and other trade barriers.(CNA/AFP/ls/PAB)