The yen jumped against the dollar on Friday, with traders on high alert for signs of fresh intervention by authorities, after a surge in the Japanese currency on Thursday that was likely the result of official buying.

The dollar fell as much as 1% to a one-month low of 157.30 yen, while the euro was down 0.3% at 172.04 yen.

It was not immediately clear what was behind the latest move.

(Reporting by the Breaking News markets team; Editing by Alun john)