Metro officials are scheduled to announce today that the transit agency will begin conducting random inspections of riders' backpacks and packages. Details will be announced at a 10 a.m. news conference by Metro Transit Police Chief Michael Taborn and Metro General Manager John B. Catoe Jr.

Former transit police chief Polly Hanson, who retired last year and was promoted to assistant general manager for safety and security, had long sought to conduct random bag inspections, but Catoe resisted in the past.

The announcement comes as the transit system faces an increase in robberies, thefts from vehicles at Metro parking lots and assaults on bus operators.

Transit security has been a growing concern since the Sept. 11, 2001, terrorist attacks and later bombings of commuter trains in Madrid, London and elsewhere. Metro, which has the second-busiest subway in the country after New York's, carries 1.2 million riders on a typical weekday.

In taking this action, Metro is joining the New York and Boston transit systems, which began random bag inspections after bombings in London's transit system in 2005.

New York's random bag searches have prevailed in court despite a lawsuit by the New York Civil Liberties Union.

The New York City Police Department, not a separate police agency, is in charge of police activities in that transit system. New York police said 2,600 officers are assigned to the 700-mile subway system, which carries nearly 5 million riders daily.

Transit officials across the country have been pressing in recent years for more federal funding for security, arguing that the federal government funds security for planes and airports. About 2 million people fly each day, compared with 34 million who ride mass transit.