Top cellphone maker Nokia Oyj revamped its management team for the second time in seven months, placing veterans in two key roles to revive its core business units and fend off rivals like Apple Inc.

Nokia's management has been under increasing criticism from analysts and shareholders as its share price has missed the market's recovery, and the firm's profits are set to miss the economic upturn this year as its smartphone portfolio flounders.

Sales chief Anssi Vanjoki will lead a new business unit, which will include company's smartphones and services operations, while Mary McDowell will take over the company's key mobile phones unit from Rick Simonson, who will retire.

"It is really surprising how often Nokia is reorganizing management ... investors should be worried about the pace," said Swedbank analyst Jari Honko.

Nokia has long said it aims to shift executives around to keep management fresh, but the timing of Nokia's latest reshuffle having carried out a similar revamp last October reflects the steep challenges facing the group.

"Nokia is doing this to show investors that they understand -- speed is the key. Getting anyone from outside would have taken too long," said analyst Carolina Milanesi at consultancy Gartner.

Nokia has not been able to make a serious challenge to Apple's iPhone in the three years since it was introduced. Its last hit smartphone model, the N95, was unveiled in 2006.

Hurt by recession and weak portfolio, Nokia's revenue fell 19% last year, while operating profit dropped 76%.

The value of the company's brand -- one of its key assets -- dropped 58% in just one year, according to a global study by Millward Brown.

Nokia has started to build a new business by offering Internet services ranging from music downloads to e-mail, but these have so far won few paying customers.