Asian markets extended the previous day's rally on Wednesday while the dollar also built on its New York gains that came after a strong US consumer confidence survey reinforced the view of a strong economy.

The greenback was given fresh impetus against the pound and euro as Prime Minister Theresa May prepares to officially fire the gun to start Britain's exit from the European Union.

After more than a week of negativity, US traders finally saw a broad advance across equities and in the greenback as figures showed American shoppers were growing increasingly upbeat.

News that the consumer confidence index had hit a 16-year high helped soothe worries that President Donald Trump's economy-boosting agenda could have been thrown off the rails by the collapse of his healthcare bill owing to splits in his Republican party.

Friday's debacle over repealing Obamacare hammered world markets on speculation the tycoon would not be able to ram through promised tax cuts and infrastructure spending.

But Greg McKenna, chief market strategist at AxiTrader, noted the US reading "goes a long way to support the notion that the US economy is doing well".

He added: "It's not just about the hope of change via president Trump’s policies. It's about actual improvement in data flow and a real sense that the globe is reflating."

The Dow on Wall Street ended in the black for the first time after an eight-day losing streak, with a bounce in oil prices also providing support. The S&P 500 and Nasdaq also posted healthy gains.

- Pound volatility -

The dollar, which has been hammered since the Federal Reserve this month signalled a slower pace of interest rate hikes than expected, also moved higher.

It was at 111.20 yen, well up from 111.08 yen in New York and 110.60 yen in Tokyo Tuesday.

The euro and pound were also well down from a day ago, hit by May's official signal to leave the European Union, with her letter due to be delivered to Brussels later in the day.

"The pound is likely to remain quite volatile throughout (Wednesday's) session," said OANDA senior market analyst Craig Erlam in a note.

On equities markets Hong Kong edged up 0.2 percent while Tokyo gained 0.1 percent, Sydney closed 0.9 percent higher, Seoul added 0.2 percent and Singapore jumped 0.7 percent. Wellington rallied one percent while Jakarta and Bangkok also advanced.

But Shanghai slipped 0.4 percent.

In early European trade London, Paris and Frankfurt each rose 0.4 percent.

Energy firms were among the big winners as an outage in Libya wiped 250,000 barrels a day out of the global market, easing worries about a supply glut, while a US stockpiles reading came in on target.

Both main crude contracts rose more than one percent Tuesday and extended the gains in Asia.

In Hong Kong, CNOOC put on 0.4 percent, while Tokyo-listed Inpex was up more than two percent and Woodside Petroleum in Sydney jumped one percent.

- Key figures around 0810 GMT -

Tokyo - Nikkei 225: UP 0.1 percent at 19,217.48 (close)

Hong Kong - Hang Seng: UP 0.2 percent at 24,392.05 (close)

Shanghai - Composite: DOWN 0.4 percent at 3,241.31 (close)

London - FTSE 100: UP 0.4 percent at 7,372.79

Euro/dollar: DOWN at $1.0785 from $1.0813

Pound/dollar: DOWN at $1.2400 from $1.2457

Dollar/yen: UP at 111.20 yen from 111.08 yen

Oil - West Texas Intermediate: UP 25 cents at $48.62 per barrel

Oil - Brent North Sea: UP 22 cents at $51.55

New York - Dow: UP 0.7 percent at 20,701.50 (close)

source: AFP