MILAN, Oct 14 (Reuters) - Italy"s antitrust authority said on Thursday it had given a conditional green light to Nexi"s (NEXII.MI) acquisition of smaller rival SIA to create an Italian payments champion. Last month, the competition watchdog said it had opened an investigation into Nexi"s merger with SIA, citing antitrust concerns in Italy"s digital payments industry. Nexi, which in June merged with Nordic rival Nets, expects to finalise the merger with SIA this quarter, creating one of Europe"s largest payments groups. Nexi said in a statement it would implement within the required timeframe the measures demanded by the authority to clear the deal. "Today"s authorisation is a further step towards the closing of the transaction, which will be completed as soon as practicable," Nexi added. The watchdog said in a statement that the measures imposed were aimed at avoiding discrimination and granting efficiency to any potential new players in the sector. It added that the merger could strengthen or create a dominant position in some specific sectors, such as domestic card processing and clearing services, although the situation was expected to be temporary. As a result, it has asked Nexi to waive an exclusivity clause in contracts with equensWorldline with reference to domestic processing and non-SEPA (Single Euro Payments Area) clearing services, and to sell non-SEPA clearing contracts that the group currently has with banks. Reporting by Elisa Anzolin, editing by Giulia Segreti, Kirsten Donovan and Susan Fenton