Citigroup, one of the world's largest credit card issuers, has experienced growth in credit card acquisitions in the UAE of 2.5 times over the past year, the bank said. In Bahrain and Poland, the bank's credit card business has increased on average by about a third over the last two years, it said.

"UAE, Bahrain and Poland are our high performers. We have very good positions in regard to our credit card business in UAE, Bahrain and Poland," said Anil Wadhwani, chief executive of consumer and commercial banking for Citigroup in EMEA.

Lending to consumers in Europe, the Middle East and Africa rose by 10 percent to $6.7 billion during the first quarter, the fastest growth by region globally, according to the bank's latest earnings presentation.

Economic growth in the UAE is forecast by the IMF to reach 3.2 percent in 2015, with Bahrain's growth estimated by the fund at 2.7 percent. Poland's economy has outshone most others in the European Union by growing through the global financial crisis.

Those markets are in contrast to Russia, where the bank has been reducing its exposure in recent months as sanctions bite against the economy.

In Britain, where the bank does not have a credit card business, its debit card business was doing "reasonably well," said Wadhwani.

It is in the process of exiting its three other consumer markets in the region -- Egypt, Czech Republic and Hungary -- moves that should be completed this year.

More than half of the bank's consumer lending globally during the first quarter was in North America, with EMEA representing only 2.4 percent of the total, according to the bank's latest earnings presentation.

Like many other banks, Citigroup has been focusing on growing its wealth management business for high net worth individuals, particularly as tight net interest margins pressure revenue from lending across much of the region.

The UAE and Bahrain offer particularly fertile ground for that, with both countries featuring in the top 12 of a 2013 Boston Consulting Group index of countries with the highest density of millionaire households in the world.

"It's growing at a very fast pace, particularly those with assets over $100,000 up to $25 million," said Wadhwani.

(Reporting By Tom Arnold; Editing by Keith Weir)

By Tom Arnold