NEW YORK, Feb 26 (Reuters) - Visa Inc (V.N), the world's largest credit card network, said on Thursday that processed transactions kept growing at high single-digit rates in January, despite a global economic slowdown.

Total processed transactions, which represent transactions handled by VisaNet, increased 8 percent in the company's fiscal first quarter, which ended Dec. 31.

The growth opportunity remains substantial, Chief Financial Officer Byron Pollitt said at a Goldman Sachs conference.

However, cross-border volumes fell in January, as companies and consumers around the world trimmed travel expenses, he added.

Visa is partially insulated from the credit crisis because it processes transactions rather than lends itself. The company posted higher-than-expected results for its fiscal first quarter, helped by lower expenses and an increase in the prices it charges to banks.

But the company lowered its outlook for net annual revenue growth to a high-single digit percentage from the low end of a prior 11 to 15 percent range, amid the fall in consumer spending and a fast deterioration of the global economy.

Pollitt reiterated he was cautiously optimistic that Visa could achieve its revenue growth target, assuming some recovery in the U.S. economy and in cross-border volumes by early 2010.

Visa shares were up 99 cents or 1.8 percent to $56.41 in afternoon trading on the New York Stock Exchange. (Reporting by Juan Lagorio, editing by Gerald E. McCormick)