Nokia, the world's largest cell phone maker, unveiled three new smartphone models on Tuesday, trying to claw back market share at the lucrative to pend of the sector.

Nokia is in the middle of a major management revamp, with the departures of its chief executive and chairman announced last week and its top internal candidate for the CEO post resigning on Monday.

The new models -- E7, C7 and a new version of the C6 -- all come with large touch screens and use the latest Symbian software. They were unveiled in London.

Nokia still controls around 40 percent of the global smart phone market volume, but has lost out to Apple and Research in Motion's Blackberry in the fatter-margin market for the most expensive cell phone models.

"The products are a clear improvement from the N97 but we know they are not where Nokia needs to be yet, and any other promise around 'we are working on it' would have not convinced anyone," said Gartner analyst Carolina Milanesi.

"A new CEO and the old guard stepping down might give investors more confidence that things are really changing."

Last week, Nokia announced it was hiring Stephen Elop, a Microsoft executive with Silicon Valley credentials, to replace embattled chief executive Olli-Pekka Kallasvuo and renew its drive to compete with Apple.

On Monday, Nokia's smartphone and services chief Anssi Vanjoki -- an outspoken and respected figure in the mobile phone industry who had been considered the most likely internal candidate to replace Kallasvuo -- announced his resignation.

Underlining the scale of the change, chairman Jorma Ollila,who led Nokia's transformation from a rubber boots-to-TVs conglomerate into a mobile phones giant in the 1990s, said last week he would step down shortly.