A coalition of environmental groups accused state regulators Monday of allowing low-level radioactive waste from the former Santa Susana Field Laboratory to be illegally disposed of in landfills not licensed to receive such material.

Consumer Watchdog,  the Center for Race Poverty and the Environment, and others said debris from six structures from the former nuclear research facility already had been delivered to municipal landfills and metal and concrete recyclers.

The environmental groups also threatened to seek a court order to stop the demolition and disposal of the plutonium fuel fabrication building if the state does not step in within 24 hours.

In 1959, the lab in the western San Fernando Valley was the site of the country’s first partial nuclear meltdown. The property is now owned by Boeing Co. and NASA and is being cleaned up.

“The state is doing the opposite of protecting the public,” said Liza Tucker of Consumer Watchdog. “It’s helping to expose the public to radioactive contamination. It’s inconceivable.”

But state officials insisted that the demolition and disposal of buildings has been legal and safe. Moreover, they said demolition of the plutonium building won't occur until it is reviewed by the U.S. Environmental Protection Agency.

Boeing officials could not be reached for comment.

Officials from the state Department of Toxic Substances Control said in a statement they are still reviewing the group's claims and would comment more fully later.