Google paid tech rival Apple $1bn in 2014 to keep its search function the default option on iOS devices, Bloomberg reports .
Analyst firms, such as Morgan Stanley , have quoted the $1bn figure in the past, but this appears to be the first time that a reference has been found in court documents.
"It's a very lucrative business to be the browser of choice on a device or the search engine on a device," Chris Green, a technology analyst at consultancy firm Lewis, told the BBC.
Other details about how Google manages its services emerged this week - including the fact that the firm removed 780 million "bad" advertisements from its sites last year.
