(Adds detail from statement, comment from analyst call) MILAN, May 13 (Reuters) - Italian payments group Nexi on Thursday improved its outlook for 2021 revenues and said transactions had accelerated from mid-April as COVID-19 lockdowns eased, after reporting better-than-expected turnover for the first quarter. Nexi shares jumped on the results, briefly triggering an automatic trading suspension. They rose 3.4% by 1201 GMT. The company said it hoped to grow revenues by a high single-digit or double-digit percentage this year, compared with the mid-to-high single digit rise it had guided towards in February. “Starting from mid-April, transaction volumes rapidly recovered on the wave of the easing of restrictions and a progressive reopening plan,” Nexi said.