American Express Co. AXP is looking at large international acquisitions that will help it benefit from booming demand for mobile payments and online commerce in emerging markets, said Executive Vice President David Messenger.The New York-based company, the biggest credit-card issuer by purchases, is considering deals in developing regions such as China, and investments in or purchases of smaller Silicon Valley startups with valuable technology, Messenger said in an interview this week. Last year, American Express agreed to acquire Loyalty Partner, a marketing firm with customers mainly in Germany, Poland and India, for $660 million.“You shouldn’t assume that’s the largest acquisition we can do,” said Messenger, who was hired last year to run a new online and mobile business unit at American Express. “We are very active, and acquisitions are a key component of our strategy.”American Express wants to gain a bigger foothold in the growing market for Internet commerce and payments over wireless devices, seeking to challenge rivals such as Visa Inc. V and Google Inc. GOOG, which have announced their own mobile-transaction services. Payments made with mobile phones alone will reach $670 billion globally by 2015, up from $240 billion this year, according to consultant Juniper Research.In developing countries such as India and China, a growing number of consumers are acquiring credit cards and smartphones. China will surpass the U.S. as the world’s largest credit-card market by 2020, MasterCard Inc. MA said last year.Mobile TransactionsAmerican Express executives expect new payment methods, such as transactions made on mobile phones, to leapfrog traditional plastic cards in those countries, Daniel Schulman, group president of enterprise growth, said in August at a company meeting.Acquisition targets may be similar to Loyalty Partner, David Robertson, publisher of industry newsletter the Nilson Report, said in an interview.“That loyalty marketing company is indicative of what AmEx sees as a model,” said Robertson, who is based in Carpinteria, California. “There will be indigenous companies in emerging markets AmEx may see as desirable.”Robertson said the company may seek to generate revenue from special offers and marketing programs, in addition to payments.American Express is interested in making “targeted” acquisitions of companies “with unique assets that complement our businesses and capabilities,” Chief Executive Officer Kenneth Chenault said in August.