* Dollar rebounds on hawkish comments from Fed's Williams

* Fed Vice Chair Fischer also gives upbeat economic assessment

* Dollar pulls further away from 8-week lows vs euro, yen

* Pound hit by speculation UK may begin Brexit talks early 2017

By Shinichi Saoshiro

TOKYO, Aug 22 (Reuters) - The dollar extended modest gains against the yen and euro early on Monday after it rebounded in recent days as U.S. Federal Reserve policymakers took an upbeat tone on the economy and expressed support for a near-term U.S. interest rate hike.

The dollar was up 0.4 percent at 100.610 yen, pulling further away from an 8-week low of 99.550 struck early last week.

The euro was down 0.2 percent at $1.1300, adding distance between a 8-week peak of $1.1366 reached on Thursday.

The U.S. currency received a lift on Friday after San Francisco Fed President John Williams said a rate hike in September should be in play.

Fed Vice Chairman Stanley Fischer also gave a generally upbeat assessment of the economy's current strength, saying on Sunday that the central bank is close to hitting its job and inflation targets.

The currency market swayed back and forth last week on conflicting views towards U.S. monetary policy.

The greenback initially gained on hawkish comments from New York Fed President William Dudley and Atlanta Fed President Dennis Lockhart, but dollar bulls were disappointed after the July Fed policy meeting minutes suggested the central bank was not in a hurry to increase rates.

Investors awaited Fed Chair Janet Yellen's speech in Jackson Hole, Wyoming on Friday during a global gathering of central bankers for more concrete policy hints.

"Market attention will be squarely focused on US Fed Chair Yellen's speech at Jackson Hole. We believe she may use the opportunity to signal the Federal Open Market Committee's growing confidence in the outlook for activity and inflation," wrote strategists at Barclays.

"Given the low market expectations for a September or December Fed rate hike, a repricing at the front end of the rates curve should drive a near-term rebound in the USD."

Federal funds futures on Friday suggested traders saw a 53.5 percent chance of a Fed rate hike this year, up from 48.8 percent on Thursday, CME Group's FedWatch programme showed.

Sterling was on the defensive after dropping 1 percent against the dollar on Friday on speculation that Britain could formally begin the process of leaving the European Union early next year.

The pound was down 0.1 percent at $1.3055 after being knocked away from a 2-week high of $1.3186 on Friday.