The South Portland company says acquiring ExxonMobil’s Esso Card would add $35 million in annual revenue.

WEX Inc., a credit card payment processing company, said Friday it plans to acquire ExxonMobil’s European commercial fuel card as it expands its international presence.

Terms of the planned acquisition of the Esso Card were not disclosed. Under the proposed deal, WEX will purchase ExxonMobil’s commercial fleet fuel card program, which includes operations, funding, pricing and sales and marketing in nine countries in Europe.

WEX said the deal, which is expected to close late in 2014 or early 2015, would add about $35 million in annual revenue.

South Portland-based WEX, formerly known as Wright Express, said the anticipated deal is subject to completion of an employee information and consultation process, and approval from competition authorities.

“Today’s announcement represents a significant milestone for WEX, as building our on-the-ground presence in the European market has been a key element to our international expansion strategy. The addition of the Esso Card program to our offering will establish our presence in the European fuel card market,” said Michael Dubyak, WEX chairman and chief executive officer.

WEX said it will make investments relating to the integration of operations and systems. It is anticipated that these investments will occur over a two-year period. The amount of the investments was not disclosed.

WEX has grown through a series of acquisitions, including last year’s $369 million deal to buy fuel card company Fleet One from private-equity firms. Other recent deals include buying 51 percent of UNIK SA, a Brazilian provider of payroll cards, for about $21.9 million, as well as acquiring CorporatePay, a London-based provider of corporate prepaid cards for the travel industry, for about $27.5 million in cash.

Jessica Hall can be contacted at 791-6316 or at:[email protected]Twitter: JessicaHallPPH