Nokia said on Monday it would defend itself vigorously against a class action complaint filed in the United States that claims the firm and its top executives hid some product delays from investors in 2008.

"Nokia has reviewed the allegations contained in the complaint and believes that they are without merit," the company said.

The City of Roseville Employees' Retirement System filed the case on Feb 5 against Nokia Corporation, chief executive Olli-Pekka Kallasvuo, then-chief financial officer Rick Simonson and Kai Oistamo, head of Nokia's phone business.