BEIJING/HONG KONG, Oct 25 (Reuters) - Global credit rating agency Moody's downgraded Fosun International Ltd by one notch on Tuesday and revised its outlook to "negative" from "ratings under review" amid concerns over the firm's accelerated asset sales.

The downgrade to B2 from B1 followed the Chinese conglomerate's announcement last week that its units would sell a combined 60% stake in Nanjing Nangang Iron & Steel United for up to 16 billion yuan ($2.19 billion), a move that would ease the firm's liquidity and debt burdens. Fosun and its units had earlier cut stakes in firms such as New China Life Insurance and Shanghai Yuyuan Tourist Mart Group.

Fosun, controlled by billionaire entrepreneur Guo Guangchang, was once one of China's most aggressive dealmakers overseas, buying high-profile assets including resort brand Club Med.

While the latest divestments will bring in cash, a roughly 30% decline in the market value of Fosun's key holdings between the end of June and Oct. 20 from shareholding dilution and share price falls has eroded its funding headroom, Moody's said in a statement.

Weak market sentiment means Fosun is likely to face difficulties in refinancing its sizable short-term debt in bond markets both onshore and offshore, the ratings agency said.

Fosun's cash on hand at the holding company level is insufficient to cover its short-term debt maturing over the next 12 months, Moody's added.

In response to a Reuters query, Fosun on Wednesday referred to a statement from Monday that the company had terminated its business engagement with Moody's rating service and ceased to provide relevant information to the agency from Oct. 12.

A Citigroup report on Tuesday said the company planned to sell 50 billion to 80 billion yuan of non-core assets within the next 12 months, including non-controlling stakes in Alibaba-backed logistics platform Cainiao, resources and metals firm Jianlong and property assets.

Fosun also expects to gradually repay the outstanding senior notes and increase borrowings from banks, the report said.

In response, a Fosun representative said on Wednesday that the company plans to continue to optimize its portfolio and to improve its capital buffer by selling some non-core assets.

Bloomberg reported on Tuesday that Fosun was reviewing options for its European financial holdings.

The Fosun representative on Wednesday referred to the company's earlier response, included in the Bloomberg story, that the group has no current plans to sell those.

($1 = 7.3089 Chinese yuan renminbi) (Reporting by Roxanne Liu in Beijing and Kane Wu in Hong Kong; Editing by Mark Potter, Christian Schmollinger and Jamie Freed)