The cautious end to the week followed a drop on Wall Street, with sentiment also jolted by geopolitical concerns after a suicide attack at Kabul airport that left dozens dead, including 13 US servicemen.

While the spread of the Delta variant of Covid has raised concerns about the global recovery outlook, the general consensus is that the vast sums of financial support provided by the Fed will likely come to an end next year as the economy gets back on track.

Powell's address to the annual Jackson Hole symposium of central bankers and economists later Friday will be closely watched for an idea about plans to reduce the bond-buying that has helped support the pandemic recovery, though a timetable is not yet expected.

Analysts say the timing of the taper is crucial as it could also give an indication of when to expect interest rates to go up.

Still, three leading Fed officials have called for the bank to begin winding down soon.

Dallas Fed president Robert Kaplan said he was eyeing an October move or shortly after.

The hawkish Kaplan had surprised many last Friday by saying he was open to rethinking his view on withdrawing support in light of the spread of Delta, but in an interview Thursday said his latest position was based on conversations with business contacts.

Meanwhile, St. Louis boss James Bullard called for a start later in the year, a call echoed by the Kansas City Fed's Esther George.

"An announcement on tapering is highly likely to come before the end of the year, something even the doves on the committee seem to agree on," said National Australia Bank's Tapas Strickland, pointing out that policy meetings are set for September, November and December.

"What will be as much, if not more important than the start date will be how quickly the Fed decides to taper and whether the Fed attempts to de-link the market's perception that tapering 'starts the clock ticking' on rate hikes."

- All about timing -

Michael Hewson of CMC Markets added that "the timing of any decision likely to be dependent on how good next week's August payrolls report is likely to be".

"We hear a lot about the risks around the Delta variant, and waiting for the risks to subside," he added. "However we could be waiting a long time for that to happen. The virus is here to stay, and it's how we learn to live with it that matters now as we head into the winter months."

Traders ended the week on an uneasy note.

Hong Kong ended flat but was weighed by a report saying China was planning a further tightening of rules for its firms to list overseas, making it even harder for them to raise cash in the lucrative US markets.

Tokyo, Sydney, Singapore, Manila and Jakarta also fell.

But Shanghai was buoyed by a report that China's central bank was looking at fresh ways to support businesses, with a cut in the amount of cash that lenders must keep in reserve being considered. There were also gains in Seoul, Wellington, Taipei, Mumbai and Bangkok.

London edged up with Frankfurt in early trade while Paris slipped.

Oil prices, which have enjoyed a strong run this week after recent hefty selling, saw more big gains as traders buy into the view that Delta's spread will only delay the economic recovery and demand will continue to improve.

OANDA's Edward Moya said WTI will likely hover around $68 a barrel until OPEC and other key producers signal their plans for output next month and whether a storm in the Gulf of Mexico will hit supplies.

"A big question for energy traders remains what will happen with Iran sanctions and if they are lifted how much crude could rush back to the market," he added, referring to talks with Tehran over its nuclear programme.

"The oil market is still heavily in deficit, but eventually Iranian crude will be a primary catalyst fuelling oversupply fears later in 2022."

- Key figures around 0810 GMT -

Tokyo - Nikkei 225: DOWN 0.4 percent at 27,641.14 (close)

Hong Kong - Hang Seng Index: FLAT at 25,407.89 (close)

Shanghai - Composite: UP 0.6 percent at 3,522.16 (close)

London - FTSE 100: UP 0.1 percent at 7,130.85

Dollar/yen: UP at 110.11 yen from 110.04 yen at 2130 GMT

Pound/dollar: UP at $1.3716 from $1.3698

Euro/dollar: UP at $1.1761 from $1.1755

Euro/pound: DOWN at 85.75 pence from 85.79 pence

West Texas Intermediate: UP 1.9 percent at $68.73 per barrel

Brent North Sea crude: UP 1.8 percent at $72.33 per barrel

New York - Dow: DOWN 0.5 percent at 35,213.12 (close)

dan/mtp

NATIONAL AUSTRALIA BANK