The District of Columbia Department of Housing is moving to block plans to convert two rental apartment buildings in the Van Ness Center complex into cooperatives.

Mimi Jones, director of the department's condominium and co-op office, said yesterday that developers of the project have been formally notified that they have no legal authority to convert the project.

All new condominium and co-op conversions are banned by a City Council moratorium that runs until this summer, she said.

A real estate firm controlled by Conrad Cafritz has signed a contract to purchase the 1,058-unit Van Ness South and Van Ness East projects for $60 million.

The Cafritz company, Investment Group Development Corp., already has made one of the three buildings in the project into cooperatives. If the two remaining buildings are converted, the complex at Connecticut Avenue and Van Ness Street NW would become one of the largest cooperatives in the District of Columbia.

Investment Group Development notified tenants of its plans to co-op the buildings last week.

Representatives of Investment Group Development could not be reached for comment yesterday.

Jones said, however, the developers failed to obtain a certificate of eligibility for the project before the city council last spring blocked the trend toward condominium and cooperative ownership.

In a condominium, residents buy their own apartment and share cost of common facilities; in a cooperative, residents own shares -- based on the value of their unit -- in a non-profit corporation that owns the project.