The number of mobile phones in use worldwide has topped five billion, boosted by soaring demand in emerging markets India and China, a study by Swedish telecoms giant Ericsson showed.

The world's fifth-billionth mobile phone subscription was recorded on July 8, the company said in a statement, with the market having increased almost seven-fold in 10 years.

"In the year 2000, about 720 million people had mobile subscriptions, less than the amount of users in China alone today," Ericsson said.

The number of mobile subscriptions increases by two million a day, "largely thanks to emerging markets like India and China," it added.

An Ericsson spokesman said the study's term "subscriptions" included both billed contracts with providers and the 'pay-as-you-go' formula, popular in emerging markets.

Since one person can have more than one mobile phone subscription, the five billion mark does not necessarily mean five billion people own a mobile phone.

According to the United Nations, the world's population is around 6.8 billion people.

Ericsson added mobile broadband subscriptions are growing at a similar pace and are expected to reach 3.4 billion by 2015, up from 360 million last year.

The mobile giant predicts 80 per cent of all people accessing the Internet will soon do so via a mobile phone.