Nokia said its second-quarter sales would be lower than expected on flagging demand for its smartphones, which face steep competition from Apple’s iPhone and other high-end devices.

“We are experiencing greater than expected pressure, particularly at the high end of our smartphone portfolio,” said Nokia CFO Timo Ihamuotila in a conference call with analysts. “Multiple factors are negatively impacting Nokia’s business to a greater extent than previously expected.”

Blaming the competitive environment for high-end phones, shifts toward less profitable products and the recent depreciation of the Euro, Nokia said its second-quarter sales will come in at the low end, or slightly below, its previous estimate of between Euro 6.7 billion ($8.2 billion) and Euro 7.2 billion.

The company, which holds the dominant share of the global handset market, said the value of its market share would be “slightly lower” in 2010 compared to last year. Nokia’s market share is expected to be flat in terms of shipment volumes.

Nokia’s shares fell about 10 percent to $8.96 by 10 a.m. Central in trading on the New York Stock Exchange.