LONDON: WhatsApp, the instant messaging service, has overtaken Facebook's own Messenger service to become the top chat app in the world outside of China, a new survey has revealed.

According to the latest Mobile Messaging survey by GlobalWebIndex, an online market research firm, WhatsApp was used by nearly 40% of the worldwide mobile internet audience each month of its survey covering Q2 2014.

Based on the usage of instant messaging tools by 600m adults aged 16-64 across 32 markets, the survey found the audience for this activity has grown 30% over the past two years.

Despite the growth of WhatsApp, which Facebook is in the process of acquiring for $19bn, Facebook Messenger saw a sharp rise in usage in some countries. In the UK, for example, it has increased from 27% in Q4 2013 to 40% by Q2 2014.

GlobalWebIndex attributed this to Facebook's decision to remove the messaging component from its main app and transfer it to the Messenger service.

After Facebook Messenger were Skype (32%) and Line (10%) in terms of global usage, but other apps tracked in the survey – such as Snapchat and WeChat – were used by relatively small percentages globally or were limited to particular markets.

WeChat, for example, was the top chat app in China – perhaps unsurprisingly – and used by 84% while Snapchat was the most popular in mature markets.

Snapchat secured 14% of the mobile audience in the UK, US and Ireland, but also scored highly in Canada and Australia, and it remained very popular among teenagers. Nearly half (48%) of 16-19 year-olds in the UK used the service.

WhatsApp was most used in South Africa (78%) and Malaysia (75%), but was also dominant in Argentina, Singapore, Hong Kong, Spain and India.

In other findings, just under two-thirds of WhatsApp users reported that mobile chat apps were now one of their primary forms of communication, with over half confirming that they have overtaken SMS as the way they typically send messages.

Also, over three-quarters of WhatsApp users believed Facebook has no right to sell their personal information to gain ad revenue, and 85% were concerned about how companies might use their conversations without their knowledge.

Data sourced from GlobalWebIndex; additional content by Warc