LONDON, May 3 (Reuters) - The yen was headed for its biggest weekly gain in 17 months on Friday, helped by Japan's suspected intervention this week to pull the currency away from 34-year lows, while the dollar index fell to a three-week low ahead of U.S. jobs data.

The yen rose to a three-week high of 152.75 per dollar during Asian trade and was set to clock a weekly gain of 3.2%, its largest since early December 2022. It was last 0.3% higher on the day at 153.20 per dollar.

Traders were left on tenterhooks for any further huge swings in the yen after Tokyo was suspected to have intervened to support its currency this week, on Monday and on Wednesday, to the tune of some 9.16 trillion yen ($59.8 billion), as suggested by data from Bank of Japan.

"The market was extremely short JPY ahead of this week’s suspected FX intervention. Many investors will still be sitting on profitable positions," said Jane Foley, head of forex strategy at Rabobank.

"But given the likelihood that the Ministry of Finance could take further advantage of thinned conditions in view of this week’s holidays and the UK and Japan holiday on Monday, some will likely be minded to take profits."

Speculators held their biggest bearish bet on the yen in seven years in dollar terms in the week ended April 23, according to the U.S. markets regulator..

Francesco Pesole, currency strategist at ING, recalling the yen fall after Japan's FX intervention in September 2022, said "the second round of intervention in one week, deployed after a less hawkish than expected FOMC (U.S. Federal Open Market Committee) on Wednesday, has sent markets the message that the MoF is less tolerant of a post-intervention depreciation of the yen this time".

The Fed held interest rates steady, as expected, at the conclusion of its two-day monetary policy meeting on Wednesday.

Traders are now looking to U.S. non-farm payrolls data due at 1230 GMT, after Federal Reserve Chair Jerome Powell told reporters that interest rates might have to remain elevated for longer but shot down talk of raising them again.

The dollar index, measuring the currency against six peers including the surging yen, fell 0.1% to 105.18 after hitting earlier its lowest since April 11. It was headed for its biggest weekly fall in almost two months, down 0.86% this week.

"Today's U.S. payrolls are a huge event for markets, as the details in the jobs report will be a key test to more optimistic bets on Fed rate cuts," Pesole added.

Elsewhere, the euro ticked 0.19% higher to$1.0745, and was eyeing a weekly gain of 0.5%, its largest since March.

Sterling rose 0.16% to $1.2556 and was similarly set for its biggest weekly gain in two months, rising 0.5% this week.

NORGES BANK HOLDS RATE

The Norwegian crown rose after Norway's central bank kept interest rates on hold at 4.50%, as unanimously expected by analysts, and said cost of borrowing might stay higher for longer than previously expected.

Norges Bank said in March it could start cutting rates in September from the current 16-year high.

"The new guidance suggests that monetary policy easing may be delayed beyond that (September)," said Charlotte Ong, European FX Strategist at HSBC.

"For now, the NOK may find some relief but the near-term outlook still appears challenging."

She added that the Norges Bank has recently stepped up its daily FX purchases to 550 million crowns from 350 million crowns previously, which could dampen sentiment around the currency.

The Norwegian crown rose to its highest since April 24, and was last 0.65% higher at 10.9190.

(Reporting by Joice Alves, Rae Wee and Ankur Banerjee; Editing by Gareth Jones and Alex Richardson)