Thousands of mobile apps are misleading marketers by loading hidden ads and emulating human behaviour, with “in-app fraud” set to pass the $1 billion mark this year, according to a new report.

Forensiq, an ad fraud company, monitored network traffic of more than 5,000 titles downloaded from Google and Apple’s stores, and found fraudulent activity where apps rapidly load hidden adds, which cannot be seen by real users.

This is allowing fraudsters to collect payments from advertisers for these hidden ads.

The company said that advertisers are losing 13 per cent of their ad spend as a result of “mobile device hijacking”. Up to 700 invisible ads were loaded on a single hijacked device in an hour.

For consumers, this type of fraudulent activity can also cause a device to waste up to 2GB of data a day, and significantly drain battery.

“With mobile ad spending expected to overtake desktop spending in 2016, tracking fraudulent behaviour and raising awareness to new threats such as mobile device hijacking is essential to building a more sustainable and overall safe advertising ecosystem,” said David Sendroff, founder and CEO of Forensiq.