SINGAPORE - Gold surged past $5,000 per ounce on Monday, buoyed by safety flows amid dollar weakness following a turbulent week where tensions over Greenland rattled investors, while markets remained on tenterhooks after violent spikes in the yen.

The yen rose over 1 percent to 153.99 per dollar as of 0427 GMT, after sharp spikes on Friday sparked speculation over potential intervention. The New York Federal Reserve conducted rate checks on Friday, sources told Reuters, raising the chance of joint US-Japan intervention to halt the currency's slide.

"The market's inclination is to short the yen but the possibility of co-ordination means it no longer is a one-way bet," said Prashant Newnaha, senior rates strategist at TD Securities in Singapore.

The prospect of joint intervention to support the yen pulled the dollar lower and broadly lifted other currencies.

Japan's Nikkei dropped about 2 percent while S&P 500 futures fell 0.25 percent and European futures were 0.27 percent lower as traders awaited the Federal Reserve's policy meeting later in the week.

Oil prices rose and safe-haven gold reached its record peaks. Precious metals, including silver, have surged in a blistering rally so far this year, also aided by a softer dollar.

Intervention chatter keeps yen aloft

While authorities in Tokyo declined to comment on the yen's wild swings, sources told Reuters about the rate checks on Friday, leaving traders on edge at the prospect of an intervention that could come any time.

Japanese Prime Minister Sanae Takaichi said on Sunday her government will take necessary steps against speculative market moves.

Carlos Casanova, senior Asia economist at UBP, said the mere expectation of potential intervention could, in itself, contribute to some strengthening of the currency.

"The Japanese yen is likely to stabilize to some extent - though the catalysts for significant appreciation remain limited - while long-term yields are expected to face continued pressure at their current elevated levels."

A steep bond market rout in Japan last week had put the spotlight on Takaichi's expansionary fiscal policy as she called a snap election that is due for Feb 8. The bond market has since calmed somewhat, but investors remain jittery.

The yen was broadly firmer against other currencies too on Monday, inching away from the record low against the euro and Swiss franc and multidecade lows against sterling.

Charu Chanana, chief investment strategist at Saxo, said the rate-check style warning could help reset positioning and remind the market there’s a line near 159–160.

"With the dollar starting to look softer, this is actually a cleaner window for Japan to lean against yen weakness. Intervention works better when it’s going with the broader USD tide, not fighting it."

The dollar index, which measures the US currency against six rivals, fell as much as 0.2 percent to a four-month low of 96.996 after dropping 0.8 percent on Friday in its biggest one-day drop since August.

Investor focus this week will also be on the Fed. The central bank is expected to hold rates steady at a meeting overshadowed by a Trump administration criminal investigation of Fed Chair Jerome Powell, whose term ends in May.

In commodities, oil prices were little changed after rising about 3 percent on Friday.

Brent crude futures were flat at $65.91 a barrel, while US West Texas Intermediate crude stood at $61.1 per barrel.