UBS would own 51 percent of its joint venture, UBS Securities, if it purchases the holdings. That would make it the first global investment bank to secure majority ownership since a surprise decision by China late last year to open the sector to foreign control.

A UBS spokesman declined to comment.

Agribusiness conglomerate COFCO Group said in a statement to the China Beijing Equity Exchange on Thursday that it would sell its 14 percent stake in UBS Securities for at least 461.72 million yuan ($66.77 million).

The state-run exchange handles deals in unlisted company stakes.

In a separate statement, investment manager China Guodian Capital said it would sell a 12.01 percent stake in the joint venture for at least 396.09 million yuan ($57.30 million).

The filings said that the two stakes should be purchased together. Neither filing disclosed a buyer.

UBS currently owns 24.99 percent of UBS Securities, according to the joint venture's website, but in May it applied to the China Securities Regulatory Commission (CSRC) to raise its stake to 51 percent.

"One of the challenges for the foreign investment banks is negotiating with their joint venture partners over the purchasing of their stakes," said Ben Quinlan, chief executive of consultancy Quinlan & Associates.

Other banks, including JPMorgan Chase and Japan's Nomura Holdings, have applied to the CSRC to take majority control positions.

But, unlike UBS, neither currently has a mainland joint venture and would need to start any such operation from scratch.

The CSRC has not announced any decision about UBS' application, nor those of the other banks. The regulator did not immediately respond to an emailed request for comment about the UBS application.

UBS, unusually for a foreign investment bank, already has effective management control over UBS Securities but it and other banks have long been keen to also hold voting control.

Foreign firms have struggled to gain market share of China's potentially lucrative securities market, in part because of their lack of control of their operations and because of the difficulty of integrating their mainland ventures with their global operations.

Last year, HSBC launched its own 51 percent-owned joint venture, but did so under rules allowing Hong Kong-based companies special access. ($1=6.91 yuan)

(Reporting by Alun John in Hong Kong and Shu Zhang in Beijing; Additional reporting by Jennifer Hughes in Hong Kong, and Sumeet Chatterjee in Bali; Editing by Neil Fullick)

By Alun John and Shu Zhang