CHEVY CHASE, Md. (AP) -- Office cleaners in Montgomery County and Baltimore are threatening to strike as early as next week if they are not offered substantial pay increases and other benefits.

Office cleaners represented by the Service Employees International Union are in negotiations for a new contract with the Commercial Building Cleaning Contractors Association. Their current one expires December 31st.

Union official Jaime Contreras says some of the buildings that could be affected include the headquarters of Legg Mason in Baltimore, the Discovery Communications offices in Silver Spring and large office buildings in Bethesda and Rockville.

The union says wages for cleaners have not kept pace with big price gains in the region's commercial real estate market. Contreras says the average starting wage is roughly $7.50 an hour in Baltimore and $8.50 an hour in Montgomery County.

© 2007 The Associated Press