Video game loot boxes are acting as a gateway to problem gambling, new research has suggested.
A study by experts at the University of York and York St John University claims spending on in-game loot boxes can be as closely linked with gambling issues as alcohol dependency and drug problems.
Loot boxes are packs of in-game items players can buy using real money, but the contents of a pack are randomised and not known until after purchase.
Many of today's most popular games, including Fortnite, feature loot boxes.
The research said similarities between loot boxes and gambling could lead to increases in problem gambling among gamers, and it suggests revenue generated from loot boxes will reach 30 billion US dollars (£23.3 billion) this year.
It comes in the wake of research by the Gambling Commission suggested the number of children classed as having a problem with gambling has quadrupled to more than 50,000 in just two years.
As part of its report, the commission raised concerns that close to a million young people had been exposed to gambling through loot boxes.
It has previously voiced concerns the features are blurring lines between gaming and gambling.
On the latest research, author Dr David Zendle from York St John University called for more regulation around the gaming packs.
"The relationship between loot box spending and gambling remains serious and potentially dangerous regardless of whether loot boxes are technically considered a form of gambling or not," he said.
"We strongly recommend that authorities and regulatory bodies restrict access to loot boxes."
Co-author Dr Paul Cairns, from the department of computer science at the University of York, said: "Due to the nature of this research it is impossible to tease apart whether we are seeing a situation in which spending on loot boxes leads to problem gambling or whether problem gambling leads to spending on loot boxes. It may indeed be the case that both directions of causality are true.
"Further work is needed, but either way this research makes it clear that there is an urgent need to regulate loot boxes within the gaming industry."