* Smartphones drive demand

LONDON, March 19 (Reuters) - Companies spent 203 million pounds ($323 million) advertising on mobile phones in Britain in 2011, in a bid to reach consumers spending an increasing amount of time looking at their devices, new data showed.

The Internet Advertising Bureau and PwC said advertising on mobile phones jumped 157 percent, as an increasing number of Britons used phones to access entertainment, social networks and the internet.

Much of that demand for entertainment and information via the mobile phone has been driven by the adoption of larger-screen smartphones, such as Apple's iPhone, and the many apps offering services and games.

The main advertisers came from the media and entertainment sector, while more general consumer brands were also increasing their spend, and the main types of adverts included traditional banner ads, text messages and search on mobile sites.

"Mobile advertising is gaining momentum - with growing opportunities to target consumers with a range of innovative formats, on the web and in mobile applications," Anna Bartz, strategy manager at PwC, said.

"The rapid adoption of smartphones and tablets means mobile is offering a compelling new way for brands and advertisers across all sectors to reach people, making it an increasingly powerful platform in multi-media strategies."

Marketing groups have for years seen mobiles as a logical way to reach consumers as they regularly access their phones and can receive ads suitable to their location. However, the idea has been slow to take off due to an inability to properly measure its success and differing technical standards. ($1 = 0.6292 pound) (Reporting by Kate Holton; editing by James Jukwey)

• A Permanent Economic Emergency