NEW YORK (AP) _ Imasco Ltd., a Montreal-based tobacco and retailing concern, said Wednesday it had agreed to sell its Genstar Stone Products division to Redland PLC of Great Britain for $317.5 million.

Redland, a publicly owned British corporation, provides materials and services to the construction industry.

Genstar Stone, which is based in Hunt Valley, Md., is a subsidiary of Genstar Corp., which Imasco bought earlier this year for $1.9 billion.

Imasco, which also owns Hardee's Food Systems, Imperial Tobacco and Peoples Drug Stores, has been selling off Genstar's assets except for Canada Trustco Mortgage Corp., a financial services business.

The Genstar Stone sale, which is scheduled to be completed Nov. 4, is subject to review under federal antitrust laws and approval by Redland shareholders, Imasco said in a statement issued in New York.

Imasco also announced it had completed the sale of Genstar's cement operations to Cimenteries CBR SA, a Belgian cement producer, for about $325.4 million. The deal was announced in July.

Imasco also has agreed to sell Genstar's waste-services subsidiary, GSX Corp., to Laidlaw Transportation Ltd. of Canada for $373 million.