The deal, announced in March, is the biggest in the fast-growing electronics payments industry which has seen a wave of consolidation recently.

FIS produces software for banks and asset managers as well as its financial services outsourcing business. Worldpay, spun off from Royal Bank of Scotland in 2010, is a major player in card payments.

Global payments could top $3 trillion a year in revenue by 2023 as more people switch from cash to digital payments for online and in-store sales, according to consulting firm McKinsey.

The European Commission, which is scheduled to decide on the deal by July 5, declined to comment. FIS and Worldpay did not immediately respond to a request for comment.

FIS and Worldpay shares extended gains following the Reuters report. By 1445 GMT, FIS shares were up 2.5% and Worldpay up 3.9%.

(Reporting by Foo Yun Chee; editing by Alissa de Carbonnel and Jane Merriman)

By Foo Yun Chee