The dollar retreated against most peers Monday, with warnings of wild volatility ahead as Donald Trump began his presidency promising to put America first and attacking global trade deals.

While trading floors are ravaged by uncertainty over the tycoon's plans, shares in most Asian markets rose following a positive lead from Wall Street, though Japan's Nikkei tanked as the greenback slipped against the yen.

Europe's main stock markets were down around half a percent in late morning deals.

In foreign exchange, the euro hit a six-week high against the dollar at $1.0755.

"The greenback... seems to have been shaken both by the apocalyptic tone set by Trump at his inauguration, and the global protests that greeted the former Apprentice host's ascension to the highest office in the land," said Spreadex analyst Connor Campbell.

Trump's inauguration speech Friday continued his campaign rhetoric, saying "every decision on trade, on taxes, on immigration, on foreign affairs will be made to benefit American workers and American families".

On Sunday he vowed to start renegotiating the North American Free-Trade Agreement during upcoming talks with Mexico and Canada.

"Markets are now waiting for more evidence that Donald Trump will deliver on fiscal stimulus and deregulation," Shane Oliver, Sydney-based global investment strategist at AMP Capital Investors, told Bloomberg News.

"Shares remain vulnerable to a further correction or consolidation in the next month or so."

- 'Volatile times' -

But the dollar -- which soared in November and December on expectation Trump's big-spending, tax-cutting, deregulation plans would fan inflation -- continued to struggle in January.

On Monday, the US unit was down more than four percent on the yen from the highs touched late in December. It was also well down against the euro and pound despite ongoing concerns about Britain's exit from the European Union.

"I suspect we're entering extremely volatile times for the dollar," Stephen Innes, senior trader at OANDA, said in a note.

"There remains a high level of uncertainty about the new administration's dollar policies, especially following President Trump's recent remarks on the strong dollar directed at China."

Trump last week said the greenback was too strong against China's yuan and claimed this was "killing" the US economy.

The stronger yen dragged down exporters on Tokyo's Nikkei, which ended 1.3 percent lower. Takata collapsed again, diving nearly 18 percent on fears of a drawn-out bankruptcy restructuring for the airbag maker at the centre of the biggest-ever auto safety recall.

The embattled stock, which has lost more than half its market value in a week, fell by its daily limit, extending a losing streak to a sixth session.

- Key figures at 1100 GMT -

London - FTSE 100: DOWN 0.6 percent at 7,157.02 points

Frankfurt - DAX 30: DOWN 0.4 percent at 11,583.44

Paris - CAC 40: DOWN 0.3 percent at 4,835.56

EURO STOXX 50: DOWN 0.4 percent at 3,285.66

Tokyo - Nikkei 225: DOWN 1.3 percent at 18,891.03 (close)

Shanghai - Composite: UP 0.4 percent at 3,136.77 (close)

Hong Kong - Hang Seng: UP 0.1 percent at 22,898.52 (close)

New York - Dow: UP 0.5 percent at 19,827.25 (close)

Euro/dollar: UP at $1.0729 from $1.0697

Pound/dollar: UP at $1.2454 from $1.2365

Dollar/yen: DOWN at 113.60 yen from 114.58 yen

Oil - West Texas Intermediate: DOWN 74 cents at $52.48 per barrel

Oil - Brent North Sea: DOWN 65 cents at $54.84