Yahoo! has extended its mobile display advertising system to 18 countries outside the US, as well as announcing a number of deals with advertisers to target mobile web users.

The company said brands including Hilton’s Embassy Suites, Intel, Nissan, Pepsi and Singapore Airlines had committed to buying ads on its mobile internet service.

It added: “This worldwide launch demonstrates Yahoo!’s continued focus on extending our leadership in display advertising and intension (sic) to be number one in mobile monetization.”

The move comes as both Google and Yahoo! are ramping up their mobile web services in a bid to boost earnings from display and search ads.

Vodafone has already named Yahoo! as its display ad partner in the UK – one of the countries covered by today’s launch.

The portal debuted the display ad system in the US in November last year, as well as launching mobile search ads in the US and UK in October and signing deals with operators such as 3 and Orange.

However, recent reports suggest mobile operators are mulling over the launch of their own search service.