(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. Nexi, with its agreed mergers with domestic rival SIA and Nordic peer Nets, will turn into one of Europe’s biggest payment companies. It said its core profit margin would remain broadly flat this year, “with potential upside”. Nexi confirmed the Nets acquisition will close in the current quarter and the merger with SIA in the following one. In the second half of the year Nexi also expects to close the 170 million euro acquisition of the retailers’ payment business of UBI, which is now part of Intesa Sanpaolo. Nexi has been growing rapidly through M&A deals as the sector consolidates and CEO Paolo Bertoluzzo told analysts the company continued to scout for bolt-on acquisitions. Earnings before interest, tax, depreciation and amortisation (EBITDA) rose 2% to 140 million euros in the first quarter, while revenues grew 4% to 259 million euros, ahead of company expectations. In a trading update published in April, Nexi had said revenues would broadly match the previous year’s figure in the first three months of 2021. SIA reported on Wednesday a 9% increase in revenues to 182 million euros with core profit up 8.6% to 63 million euros in the January-March period. Also on Wednesday, Nets posted a 5% drop in first quarter revenues to 241 million euros. Core profit fell 13.4% to 62 million euros. (Reporting by Elisa Anzolin; editing by Valentina Za and Elaine Hardcastle) Our Standards: The Thomson Reuters Trust Principles.