GEORGETOWN, Ky. (AP) _ Toyota Motor Corp. will expand its Camry plant now under construction in Scott County with a $300 million addition, company and government officials said Monday.

The new facility will manufacture engines, axles and steering components.

Kaneyoshi Kusunoki, president of Toyota Motor Manufacturing, U.S.A., Inc., said the company decided to locate the new facility at the Camry site to keep down costs.

''We considered such options (other sites) from the beginning,'' he said through an interpreter. ''However, considering the capacity we have at the present moment, we decided to put it here.''

The strengthening of the Japanese yen was a large factor in Toyota's decision to expand the scope of the Scott County plant, but the company has no immediate plans to expand elsewhere, Toyota Chairman Eiji Toyoda said during a news conference in New York.

''The current scope of the Kentucky expansion is all that we have on the table at the moment,'' he said.

Toyoda also said the automaker was not considering exporting cars from the United States although plans depend on the direction of the yen.

''We are in very difficult straits'' as a result of the strong yen, Toyoda said. ''This has placed us in a very awkward position.''

The new facility in Scott County will manufacture a four-cylinder, 16-valve electronic fuel-injection engine, front and rear axles and steering components for the Camry. It will employ 500 people by 1991 in addition to the 3,000 needed at the $800 million automobile assembly plant.

The production of axles is set for fall 1988, engines in fall 1989 and steering assemblies in 1990.

''Our people know that Toyota's commitment to Kentucky, which has been strengthened this morning, has been a turning point for our Commonwealth,'' said Gov. Martha Layne Collins at the news conference announcing the expansion.

Test production of the Camry will start next spring, with commercial production expected by November 1988, Kusunoki said.

Collins said there ''was no discussion of incentives'' in talks with Toyota on the expansion. Toyota was given $125 million in incentives for training and land acquisition to locate in Kentucky.

Because the new facility will be built adjacent to the main plant, Kusunoki said, ''we have no intention in asking for additional incentives in that aspect.''

He said he is not sure if Toyota will ask for additional assistance for training new employees in the expansion project.

''We will make a maximum effort ... not to ask for assistance,'' he said.

Collins said Toyota has already had ''a significant impact on Kentucky's economy'' because ''24 auto-related manufacturing plants have followed Toyota to Kentucky, creating an additional 4,000 jobs. That in itself is impressive.''

She said Toyota and the auto-related plants will have a payroll of $180 million a year they are all in full production.

Toyoda would not comment on whether Toyota would be profitable in this fiscal year, which ends June 30. Profits shrank in the last fiscal year because of a decline in exports from Japan.

Toyota also owns a plant in Fremont, Calif., in a joint venture with General Motors Corp., one of four plants in the United States producing Japanese cars.

Honda has a plant in Marysville, Ohio; Nissan makes compact pickup trucks in Smyrna, Tenn., and Mazda sedans are produced in Flat Rock, Mich.

A Subaru-Isuzu plant is under construction in Lafayette, Ind., and Bloomington, Ill., will be home to a plant that is a join venture between Mitsubishi and Chrysler Corp.