Forex-Yen in the spotlight after sudden jump

The yen held its gains on Thursday after a sudden, brief surge in the previous session that traders suspect may have been driven by government authorities, keeping pressure on the dollar ahead of a crucial U.S. jobs report.

The yen JPY= was last steady at 158.88 per dollar, having jumped 0.9% overnight, in a move that left market participants on alert for an official intervention from Tokyo.

Its rally was broad-based, with the euro falling roughly 1% against the yen on Wednesday; sterling dropped 1.15%, with both currencies nursing losses in early Asia trade.

"The yen rally was about 0.9% and it's not a big move, and I definitely don't think that was an intervention," said Carol Kong, a currency strategist at Commonwealth Bank of Australia. "But some market participants have speculated that the rally was caused by a rate check."