Updated from 3:21 a.m. EST

Vodafone ( VOD), the world's biggest mobile phone company, said first-half adjusted operating profit rose 10.5% to 5.8 billion pounds ($9.05 billion) on a revenue increase of 17%, but reduced its full-year sales forecast for the second time in four months.

Net profit in the period fell 35% to 2.2 billion pounds from 3.3 billion pounds a year earlier.

Vodafone said it expects full-year revenue in the range of 38.8 billion pounds to 39.7 billion pounds, and adjusted operating profit of 11 billion pounds to 11.5 billion pounds. In July, Vodafone said it expected full-year revenue near the bottom of 39.9 billion pounds to 40.7 billion pounds.

The company raised its free cash flow guidance for the year ending in March 2009 to 5.2 billion pounds to 5.7 billion pounds.

"Vodafone has again delivered strong cash generation and we have raised free cash flow guidance despite the reduction in underlying expectations for trading," the company said in a statement. "Our updated strategy reflects the changing economic and market conditions and it will drive execution with a continuing focus on free cash flow."

The company said it plans to cut costs under a 1 billion pound program because of the revenue slowdown.