UNC Resources Inc. of Falls Church has made a preliminary offer to acquire Texas International Co., an Oklahoma City oil and gas production and equipment firm, Texas International disclosed yesterday.

No details of the offer were revealed and UNC officials said they have nothing to add to the Texas International statement.

Texas International successfully defended itself against an unsolicited takeover bid by Gold Crown Corp. earlier this year and for the past month has been holding merger talks with NFC Corp., another Oklahoma energy company.

The UNC offer will not effect the negotiations with NFC, said John Hein, a Texas International spokesman. The two companies have closely related business and are discussing a merger through an exchange of 1.2 shares of Texas International stock for each share of NFC, he said.

Texas International's stock has traded recently for around $16 a share on the New York Stock Exchange, where UNC shares are selling for about $21.

Last May, Gold Crown Corp. offered to buy Texas International for $18 a share. After Texas International rejected the offer, Gold Crown launched a proxy fight and tried unsuccessfully to elect three of its representatives to Texas International's board of directors.