LONDON (AP) _ Guinness PLC said Friday it will join forces with a French luxury goods marketer to create a new company to hold a substantial stake in LVMH Moet- Hennessy Louis Vuitton, maker of champagne and upscale luggage.

Separately, LVMH will acquire 10 percent of Guinness, a leading British brewer that also makes Johnnie Walker Scotch Whisky and Gordon's gin. Both transactions are subject to the approval of Guinness shareholders.

Guinness said it will invest a minimum 237 million British pounds, or about $408 million, for a 40 percent stake in a joint venture company to be formed along with Financiere Agache Group of France. The new company will control their joint LVMH holdings.

Agache, a holding company that controls the Christian Dior, Christian Lacroix and Celine fashion houses, would retain 60 percent of the joint venture company.

In a statement issued from its Paris headquarters, LVMH acknowledged that Guinness and Agache have amassed a 24 percent stake in the company on a fully diluted basis.

Guinness said the agreement with LVMH represents a ''natural progression'' of their existing relationship. Last year the two companies agreed to set up a series of joint ventures to distribute their products in the United States, Japan and the Far East.

Anthony Tennant, Guinness's chief executive, called the agreement a ''major long-term strategic move. Our new partnership with Financiere Agache Group is based on our mutual and complementary interest in the wines, spirits and luxury goods businesses of LVMH.''

LVMH produces Moet et Chandon champagne and Hennessy cognac as well as perfumes and luxury leather goods. Guinness did not indicate how large a stake the joint venture company hoped to build in LVMH.

LVMH recently purchased 7.25 million Guinness shares in the open market and intends eventually to increase its holdings to 12 percent. To that end, Guinness has proposed issuing LVMH 90.8 million Guinness common shares, or about 10 percent, for about 390 million pounds, or $671 million.

LVMH said the cross-shareholding will ''reinforce the commercial ties that already exist between the two groups and allow them the stability that is required for their development.''

The move puts an end to a week of suspense about the identity of the purchasers who were behind a surge in LVMH shares in unusually heavy volume.

Analysts had speculated that Agache was one of the buyers, in line with the plans of its chairman, Bernard Arnault, to consolidate his position in the luxury goods sector through an agreement with LVMH. Guinness was also thought to be a buyer.

Some analysts speculated that both companies were able to acquire their stakes relatively unnoticed because of tension among senior LVMH officials.

LVMH hasn't commented on the reported tensions, but bankers have indicated that conflict arose between Alain Chevalier, who heads the Moet interests, and Henry Racamier, who runs the Vuitton operations.

LVMH was formed in 1987 by the merger of two prominent family-controlled companies, the baggage, perfume and champagne distributor Louis Vuitton SA and the champagne, spirits and perfume company Moet-Hennessy SA.