After a period of relative calm on tariffs, Donald Trump at the weekend accused Beijing of violating last month's deal to slash huge tit-for-tat levies and threatened to double tolls on steel and aluminium.

The moves jolted Asian markets on Monday, but hopes that the US president will speak with Chinese counterpart Xi Jinping -- possibly this week -- has raised hopes for a positive outcome.

Meanwhile, oil prices extended Monday's surge after Ukraine's strike on Russian bombers parked deep inside the country stoked geopolitical concerns.

Trump has expressed confidence a talk with Xi could ease tensions, even after his latest volley threatened their weeks-old tariff truce.

"They violated a big part of the agreement we made," he said Friday. "But I'm sure that I'll speak to President Xi, and hopefully we'll work that out."

It is unclear if Xi is keen on a conversation but Trump's economic adviser Kevin Hassett signalled on Sunday that officials were anticipating something this week.

US Treasury Secretary Scott Bessent -- who last week warned negotiations with China were "a bit stalled" -- said at the weekend the leaders could speak "very soon".

Officials from both sides are set for talks on the sidelines of an Organisation for Economic Co-operation and Development ministerial meeting in Paris on Wednesday.

The OECD slashed on Tuesday its 2025 growth outlook for the global economy to 2.9 percent from 3.1 percent previously expected. It also said the US economy would expand 1.6 percent, from an earlier estimate of 2.2 percent.

It warned "substantial increases" in trade barriers, tighter financial conditions, weaker business and consumer confidence, as well as heightened policy uncertainty will all have "marked adverse effects on growth" if they persist.

"For everyone, including the United States, the best option is that countries sit down and get an agreement," OECD chief economist Alvaro Pereira told AFP.

While there has been no movement on the issue, investors were largely upbeat.

Hong Kong gained more than one percent while Shanghai returned from a long weekend with gains, even as data indicated Chinese factory activity shrinking at its fastest pace since September 2022.

There were also gains in Sydney, Taipei, Bangkok, Jakarta and Manila, while London was flat.

Tokyo, Singapore, Wellington and Mumbai retreated with Paris and Frankfurt.

Seoul was closed for a presidential election.

- Deals queued up? -

The advances followed tech-led gains on Wall Street in the wake of forecast-beating earnings from chip titan Nvidia.

Still, National Australia Bank's Rodrigo Catril remained nervous, writing in a commentary: "The lift in tariffs is creating another layer of uncertainty and tension.

"European articles suggest the lift in tariffs doesn't bode well for negotiations with the region (and) UK steelmakers call Trump doubling tariffs 'another body blow'."

He added: "The steel and aluminium tariffs also apply to Canada, so they will likely elicit some form of retaliation from there and while US-China trade negotiations are deteriorating due to rare earth, student visas and tech restrictions, steel tariffs will also affect China."

US Commerce Secretary Howard Lutnick on Monday voiced optimism for a trade deal with India "in the not too distant future", while Japanese trade point man Ryosei Akazawa is eyeing another trip to Washington for more negotiations.

Also in focus is Trump's signature "big, beautiful bill" that is headlined by tax cuts slated to add up to $3 trillion to the nation's debt at a time of heightened worries over the country's finances.

Senators have started what is certain to be fierce debate over the policy package, which partially covers an extension of Trump's 2017 tax relief through budget cuts projected to strip health care from millions of low-income Americans.

Oil prices extended Monday's surge that saw West Texas Intermediate briefly jump five percent on concerns about an escalation of the Russia-Ukraine conflict and suggestions Washington could hit Moscow with stricter sanctions.

That compounded news that the OPEC+ producers' grouping had agreed a smaller-than-expected increase in crude production.

- Key figures at around 0810 GMT -

Tokyo - Nikkei 225: DOWN 0.1 percent at 37,446.81 (close)

Hong Kong - Hang Seng Index: UP 1.5 percent at 23,512.49 (close)

Shanghai - Composite: UP 0.4 percent at 3,361.98 (close)

London - FTSE 100: FLAT at 8,770.55

Euro/dollar: DOWN at $1.1420 from $1.1443 on Monday

Pound/dollar: DOWN at $1.3521 from $1.3548

Dollar/yen: UP at 142.90 yen from 142.71 yen

Euro/pound: DOWN at 84.45 pence from 84.46 pence

West Texas Intermediate: UP 0.9 percent at $63.11 per barrel

Brent North Sea Crude: UP 0.9 percent at $65.18 per barrel

New York - Dow: UP 0.1 percent at 42,305.48 points (close)

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