Credit card issuer American Express Co (AXP.N) topped Wall Street targets for quarterly profit and forecast annual earnings at the high end of its expected range as a strengthening U.S. economy contributed to higher customer spending.

Shares of AmEx, which ended 1.4 per cent higher on Wednesday, added another 3.6 per cent in after-hours trading.

New York-based AmEx has been investing aggressively on customer rewards to woo more high-spending customers and counter competition from major U.S. banks that have been boosting their presence in the niche premium card category.

JPMorgan Chase (JPM.N), Citigroup (C.N) and Bank of America (BAC.N) all reported growth in their card businesses in the first quarter of 2018.

"Today's results are showing good returns on the investments we've been making to drive growth in the premium sector," said AmEx Chief Executive Stephen Squeri.

AmEx said customer spending rose 3 per cent in the United States and 7 per cent worldwide in the first three months of the year.

Consumer spending, which makes up more than two-thirds of U.S. economic activity, rose in January and February.

AmEx now expects yearly earnings at the high end of its US$6.90 to US$7.30 per share forecast. Analysts on average were expecting US$7.11 per share, according to Thomson Reuters I/B/E/S.

AmEx said net income attributable to common shareholders rose to US$1.63 billion or US$1.86 per share in the first quarter ended March 31, from US$1.25 billion or US$1.35 per share a year earlier.

Analysts had expected earnings of US$1.71 per share.

Total revenue, net of interest expense, climbed 12 per cent to US$9.72 billion, topping analysts' forecasts of US$9.46 billion.