LONDON, June 23 (Reuters) - British employers are their most confident about the economy in almost five years, helped by the lifting of coronavirus restrictions, a survey showed on Wednesday, but the lack of staff to fill jobs is a growing problem. The Recruitment & Employment Confederation"s measure of business confidence surged by 21 percentage points to a net reading of +11. That was the highest level since July 2016, shortly after Britain voted to leave the European Union, and the first time the index was in positive territory since 2018. "This surge in employers" confidence in the UK economy is remarkable," Neil Carberry, REC chief executive, said. "However, we are seeing labour and skills shortages across the economy right now, which the pandemic has made worse. These could threaten to slow down the recovery if not addressed quickly," he said. Better access to training was needed, as was support for staff wanting to change sectors, he added. Britain"s economy has shown signs of a strong recovery from its slump of nearly 10% in 2020, although the Bank of England thinks it will only regain its pre-pandemic size in the final quarter of this year. REC said employers" confidence about hiring and investment was the highest since March 2016 at +29. The data was based on telephone polling of 600 employers between March 8 and May 28.