China’s Ministry of Commerce is the only remaining merger clearance required for the deal, which has been approved by more than 40 regulatory bodies worldwide including the United States and the European Union.
The proposed takeover is set to create the world’s largest hotel company with 1.1m rooms across more than 5,500 sites.
Neither hospitality group would specify why the Chinese had requested more time to complete their review, but both appeared positive that the deal would be approved.
“Marriott and Starwood continue to believe that their planned merger transaction poses no anti-competitive issues in China,” Marriott said in a statement.
The hold-up comes after a major bidding war between Marriott and a consortium led by China’s Anbang Insurance Group, which attempted a $14bn takeover of Starwood before pulling its offer on 31 March.
It came after Marriott questioned the Chinese group’s finances and warned Starwood stockholders that Anbang may be unable to close the deal.
If completed the Marriott merger will create a hospitality company with 30 brands, including Starwood’s St Regis, Sheraton and W Hotels and Marriott's Ritz Carlton and Moxy sites.