LONDON, July 30 (Rtrs) - The yen briefly jumped against the

dollar on Thursday in a move analysts said did not bear the

hallmarks of the official intervention traders are braced for,

but rather unease following a dramatic Federal Reserve meeting

and a day before the Bank of Japan meets.

The dollar dropped as low as 162.57 yen as its decline from

its day high of 163.7 yen suddenly accelerated during London

trade. It then rebounded and was last 162.7.

Traders are alert to the prospect of intervention from Japan

to prop up its stubbornly weak currency, though the move was

smaller than recent dramatic bouts of yen strengthening that

have followed official moves.

"It doesn't look like intervention just a broad-based

(dollar) selloff," said Lee Hardman senior currency analyst at

MUFG. "The market is still reacting to the Fed's update

yesterday."

A divided Fed left rates unchanged on Wednesday even as U.S.

central bank chief Kevin Warsh pledged an unwavering commitment

to bring inflation down, a message that left markets confused

about just what he was prepared to do and piled upward pressure

on Treasury yields.