In order to meet increasing demands for research facilities, Harvard Medical School is planning to construct a $250 to $300 million research complex in the Longwood Medical Area, Medical School officials said yesterday.

The proposed facility would include biomedical laboratories as well as animal breeding and research facilities. Construction is scheduled to begin in late 2000 or early 2001.

A lack of sufficient research facilities prompted "an expansion of existing biomedical research laboratories that will promote a wide-ranging program of biomedical research," according to Eric P. Buehrens, associate dean of planning and facilities at the Medical School.

The Medical School will pay for the construction of the complex, but it expects to recover the costs by leasing out space to affiliated teaching hospitals as well as through funds from research grants.

Plans for a new facility were first discussed 10 months ago at a meeting between Medical School officials and Harvard's 17 affiliated teaching hospitals, said Paul Levy, executive dean of administration at the Medical School.

"This was a vision from a long time ago, " Levy said, "but now there is a demand for research space."

Levy said Beth Israel Deaconess Medical Center, Center for Blood Research, Brigham and Women's Hospital, Dana-Farber Cancer Institute and Children's Hospital were among some affliated institutions looking to benefit from the new research facilities.

Several other building projects in the area are scheduled to begin soon, including the construction of two Children's Hospital facilities totaling $160 million. This project has raised concerns among community members about congestion and parking in the neighborhood.

The affiliated hospitals' various projects and this new complex are expected to take seven years to build; the combined total cost is expected to mushroom to $800 million.