Sina Corporation, China's leading internet news portal, is to buy the core assets of Focus Media, the country's leading digital media company, for more than $1bn in a bold attempt to seek a growth engine for its advertising revenues.

Under the deal, Sina will gain control of Focus Media's network of outdoor advertising posters and LCD screens in hotels, offices and residential buildings. Focus Media will keep Allyes, its online advertising agency business, some traditional billboards and its cinema advertising business.