* Graphic: Trade-weighted sterling since Brexit vote tmsnrt.rs/2hwV9Hv (Updates prices) LONDON, March 5 (Reuters) - The British pound lost ground against a resurgent dollar on Friday, as currency traders took some risk off the table amid rising U.S. bond yields. U.S. Federal Reserve Chair Jerome Powell failed to soothe investor concerns about a recent surge in borrowing costs as he spoke at a Wall Street Journal forum on Thursday, pushing the safe-haven dollar higher. Sterling fell to a three-week low against the dollar, briefly dropping below $1.38. It was last down 0.6% at $1.3810. The pound had reached as high as $1.42 last month - its highest level since 2018 - as optimism built about Britain’s swift introduction of COVID-19 vaccines and expectations of a robust economic recovery. “The dollar is rebounding along with longer term U.S. yields, which is triggering a reversal of trades including for the pound,” said Lee Hardman, currency economist at MUFG. “But the fundamentals are moving in a positive direction for the pound with the vaccine rollout and growing hopes of a recovery. The pound should strengthen after this near-term correction.” Analysts said British finance minister Rishi Sunak’s budget plan for the economy, which included a further extension of pandemic stimulus packages and some tax rises, could also ultimately strengthen the pound. “This should keep fiscal policy loose, which should keep the Bank of England in a hawkish mood while expecting a robust economic recovery in the next few months. This mix should keep supporting sterling beyond $1.40,” said Gaetan Peroux at UBS. Against the euro, the pound dipped around 0.1%, last at 86.24 pence. (Reporting by Iain Withers, editing by Larry King and Timothy Heritage)