Even as Societe Nationale Elf Aquitaine appears ready to consummate its takeover of Texasgulf Inc., at least one flag-waving U.S. company hopes to block the transaction with the Clayton Antitrust Act.

The squeaky wheel is International Minerals & Chemicals Corp. a company based in Northbrook, Ill., that relies on many of Texasgulf's mineral products to produce fertilizers. International has asked the Federal government-owned Aquitaine in violation of the Clayton Act, alleging that the deal would reduce the supply of fertilizers in the U.S. market.

Charging that "France and Canada are pursuing policies of government ownersip and control of industry" to the detriment of defenseless American companies, International said in a letter to the FTC that under French control "Texasgulf would export as much of its phosphate rock and phosphate chemicals to France as the French government thinks desirable."

The result would be a drop in U.S. fertilizer production in a time of shortage and a constricted market in sulfur and other products of Texasgulf, the letter says.

The deadline for FTC action is midnight tonight. Yesterday afternoon, spokemen for Aquitaine and Texasgulf said they had received no notice that the commission would act, and an FTC spokesman declined to comment.

Aquitaine's offer for Texasgulf ranks as one of the more complex corporate takeovers. Elf Aquitaine, in a friendly takeover engineered with Canada Development Corp., is offering Texasgulf's shareholders $56 a common share. A 37 percent block held by Canada Development, a minerals firm that is half owned by the Canadian government, is not eligible for the offer. Instead, Aquitaine will swap Texasgulf's Canadian assets -- principally a large copper deposit in Ontario -- for the Canada Development block plus some cash in a transaction whose value is estimated at $1.63 billion.

Aqitaine has offered to pay a total of $2.74 billion for the shares not held by Canada Development. On June 26, when Aquitaine announced its original takeover offer, it also announced it would sell 75 percent of Aquitaine Co. of Canada to Canada Development for $993 million (U.S.).

Aquitaine's original offer for Texasgulf, which met with a chilly reception in the American company's boardroom, would have paid $50 a share. Texasgulf common was selling at about $37 a share before Aquitaine announced its takeover attempt, and at about $30 a share in early June. The Texasgulf board agreed not to fight the takeover after Aquitaine raised the ante to $56 on July 1.

For two years, Texasgulf's earnings have been buoyed by rising prices for its principal products. The Company, which is based in Stamford, Conn., earned a record $325.6 million ($9.70 a share) last year on sales of $1.1 billion. Directors declared a two-for-one stock split in April. Analysts with Merrill Lynch, Piercer, Fenner and Smith Inc. see earnings slumping this year due to lower prices for metals and poor fertilizer sales.

Known as Texas Gulf Sulphur Co. until the early 1970s, Texasgulf is still strong in sulfur production. The company also has sizable production of lead, copper, zinc and phosphates, along with an oil and gas division that is small by industry standards. Sulfur and phosphates are esential for fertilizer production, a fact which is at the root of International's complaint.

More than 40 percent of Texasgulf's assets, or roughly $850 million, are in Canada. More than half its operating income last year came from its Canadian operations.

Owned 67 percent by the French government, Aquitaine concentrates in the production, refining and distributing of oil. But Aquitaine also has sizable production of sulfur and phosphates along with petrochemicals. After the proposed takeover, the French company would be left with most of Texasgulf's production of sulfur and fertilizer ingredients.