LONDON (Reuters) - Commodities group Glencore (>> Glencore International Plc) could be forced to sacrifice a slice of copper production in order to secure a green light from China this week for its planned $32 billion takeover of miner Xstrata (>> Xstrata PLC).

China's Ministry of Commerce (MOFCOM), which regulates mergers and acquisitions, has only forced sales to resolve excessive influence in a specific market in a handful of more than 500 tie-ups examined since merger regulations were introduced in 2008.

Below are the most significant such decisions:

1. April, 2009 - Mitsubishi Rayon's acquisition of Lucite

MOFCOM ruled that the acquisition of the UK plastics maker by its Japanese rival would have an impact on the market for methyl methacrylate, a product used in resins and plastics. Lucite had to sell half its annual MMA production capacity for five years to one or more third parties.

Coming just weeks after MOFCOM blocked Coca-Cola's planned $2.4 billion acquisition of juice maker Huiyuan, it was seen as a signal of a tougher stance.

2. September, 2009 - Pfizer's $68 billion acquisition of Wyeth

U.S. pharmaceutical giant Pfizer's (>> Pfizer Inc.) acquisition of rival Wyeth was the first multinational pharmaceutical filing in China. MOFCOM required Pfizer to sell its Chinese vaccine business for a chronic respiratory disease affecting pigs.

3. October, 2009 - Panasonic's acquisition of Sanyo

Following electronics group Panasonic's (>> Panasonic Corporation) acquisition of rival Sanyo, MOFCOM required divestments to avoid excessive concentration in the production of batteries.

It required the sale of parts of Panasonic or Sanyo's business in three battery markets that caused concern, making it the first time China required sales outside the country for a merger of two non-Chinese businesses.

4. October, 2011 - Alpha Private Equity Fund V's acquisition of Savio Macchine Tessili

MOFCOM approved Alpha's acquisition of Italian textile machinery producer Savio, but raised concerns about market concentration in winder and yarn quality control.

MOFCOM agreed to a remedy that involved Alpha selling its investment in another portfolio company and Savio competitor, Uster Technologies.

5. June, 2012 - United Technologies' acquisition of Goodrich

MOFCOM approved aviation equipment producer United Technologies' (>> United Technologies Corporation) $16.5 billion purchase of parts maker Goodrich, subject to the sale of Goodrich's electrical power system businesses and its share in a separate joint venture with Thales Avionics.

China was the first jurisdiction to approve the deal.

($1 = 0.6496 British pounds)

(Reporting by Clara Ferreira-Marques; Editing by Will Waterman)