Phone giant Nokia has unveiled a free map and navigation service for its handsets that analysts cite could challenge stand-alone sat-nav devices.

A latest version of Nokia's mapping service Ovi Maps will possesses stored maps, facilitating turn-by-turn voice guidance for 74 countries, in 46 languages for walking and driving navigation for free, thereby washing out the need to update and download latest ones over the network, Nokia claimed on Thursday.

Ovi maps will initially be available on 10 handsets and will offer so-called "turn-by-turn" navigation, similar to that in existing GPS devices. In addition, it will facilitate travel guides as Lonely Planet along with the facility for accessing Facebook.

Nokia said that it expects third-party developers to build new applications for the service and would be preloaded on all compatible phones offered by Nokia from 21 January.

"It's like a giant mash-up environment", said Anssi Vanjoki, Executive Vice President of Nokia at the launch.

CCS Insight claimed that the service could trigger "Nokia's concern about falling share" in the smartphone market to competitors such as the iPhone and Blackberry.