An American firm said Tuesday it had agreed with a Soviet company to try to sell or lease MiG-29 fighters to the Pentagon for use in training. However, the Soviet firm denied there was any such deal and said it was talking only about civilian aircraft.

The Pentagon said it would have a statement Tuesday afternoon.The apparent misunderstanding broke into the open at a news conference called by International Technical Expertise Ltd. of Dunn Loring, Va., jointly with the Soviet firm, ELF-90.

ITX President Stephen Rohrkamper said, "Operating under a broad memorandum of understanding, we will be pursuing the sale, lease or service contract employment of the MiG-29 aircraft in Defense Department training programs."

Rohrkamper said the agreement also called for the sale of aircraft parts and materials to the U.S. aviation industry and the possible operation of an independent air charter service across Eurasia.

The memorandum of agreement was not specific, merely calling for the firms to "work together to locate and sell products and services."

Anatoly P. Alekseev, managing director of ELF-90, was asked whether he understood this to include sale or lease of MiG-29s. "Certainly not," said Alekseev, who spoke through an interpreter.

Peter M. Movtchan, senior expert of ELF-90, said in English that there had been discussion of possible markets for MiG-29s, including museums, but "never about price or something like that" and added, "We have no deal" concerning the sale of the MiGs.

Sergey I. Tatarenkov, export-import representative of the Soviet Consulate, said discussions in which he took part dealt with civilian aircraft.