Visa has reported better-than-expected quarterly earnings and said it expects full-year profit at the high end of its forecast.

The company is due to benefit from the purchase of Visa Europe and big credit-card portfolio wins in the US. 

Visa, the world's largest payments network operator, also announced a $5 billion share buyback programme. 

The company said total payments volume jumped 37.2% to $1.73 trillion in the second quarter ended March 31, on a constant dollar basis. 

San Francisco-based Visa, like rival MasterCard generates revenue by facilitating credit and debit-card transactions. 

The growth in payments volume was helped by the addition to Visa's results of Visa Europe, a former subsidiary Visa bought in June last year in a deal worth as much as $23 billion. 

Visa Europe made up nearly a fifth of total payments volume.

Payments volume in the US, Visa's biggest market, increased 11.7% on a constant dollar basis, helped both by major portfolio contracts as well as a stronger economy. 

Warehouse club retailer Costco and USAA, one of the largest US issuers of credit and debit cards, switched their card portfolios to Visa last year, in a competitive environment where large portfolios are hotly sought-after by payment networks. 

A healthier US economy, which has seen strong jobs growth and rising incomes in the first quarter of 2017, bodes well for consumer spending - a key economic indicator for payments processors like Visa. 

The trends, while boosting quarterly profit and revenue, also helped Visa update its full-year forecast. 

The company now expects adjusted profit at the high end of its forecast for a mid-teens percentage point increase. 

Visa also said it expects full-year revenue at the high end of its forecast for a 16-18% increase.

The company said its net income fell to $430m or 18 cents per share in the second quarter, from $1.71 billion or 71 cents a share, a year earlier. This reflected a $1.5 billion one-time charge related to Visa Europe. 

Excluding once-off items, Visa earned 86 cents per share, beating analysts' average estimate of 79 cents, according to Thomson Reuters.

Visa said its net operating revenue rose 23.5% to $4.48 billion. Analysts on average had expected $4.29 billion.