China has extended its review of Marriott International Inc's acquisition of Starwood Hotels & Resorts Worldwide Inc by up to 60 days, the companies said on Monday.

The Ministry of Commerce review is the only remaining merger clearance for the deal, which is expected to create the biggest hotel group in the world with a combined enterprise value of $36 billion and 1.1 million rooms.

Hilton Worldwide Holdings, which would be No 2 behind the combined group, has 775,000 rooms.

Marriott and Starwood did not say why the ministry needed more time and said their planned merger did not create any anti-competitive issues in China.

The merged group would become the largest hotel operator in China, with a 4.1 percent market share, followed by Homeinns Hotel & Management at 4 percent and China Lodging Group at 3.9 percent, data from research firm Euromonitor International show.

Marriott's deal to buy Starwood, the operator of Sheraton and Westin hotels, has been cleared by antitrust authorities in more than 40 countries and territories including the United States, the European Union and Canada.

The shareholders of both companies approved the deal in April.

The Chinese ministry has developed a reputation as a tough deals regulator, but it has only blocked two transactions since China's Anti-Monopoly Law came into force in 2008, compared with 1,447 unconditional clearances, according to data compiled by law firm Norton Rose Fulbright.

The regulator generally prefers to impose remedies such as asset divestments on transactions it believes could harm competition, taking this approach in 26 cases, Norton Rose Fulbright research shows.

Last month, the ministry approved AB InBev's $100 billion-plus takeover of rival brewer SABMiller Plc subject to SABMiller divesting some Chinese assets. It also extended InBev's review to phase-three, but did not make full use of the extra time.

A Chinese company, Anbang Insurance Group Co, abandoned its pursuit of Starwood in April after a bidding war that resulted in Marriott increasing its cash-and-stock bid by $1 billion. The deal is currently valued at about $13.4 billion.

While Anbang had offered $14 billion in cash, an acquisition by the Chinese firm probably would have faced scrutiny by the Committee on Foreign Investment in the United States on national security grounds