"Despite the lengthening global supply chain, every company that does business in this state must follow the law and protect consumers from lead and other toxic materials," California Attorney General Jerry Brown said in a statement.

The lawsuit follows a series of recalls this year that have led to millions of toys being taken off store shelves. Many of the recalled toys were made in China.

Gareth Lacy, a spokesman in Brown's office, said the attorney general hoped the companies would settle the lawsuit by agreeing to increased inspection, testing and lower lead levels.

The state can require companies to put warning labels on products that contain hazardous materials and or require companies to adopt more rigorous inspection procedures.

The US Consumer Product Safety Commission has recalled millions of toys this year because they contained excessive amounts of lead. Other toys have been recalled because they contained other toxic substances and small parts that could be swallowed.

Mattel, the world's largest toy maker, makes about 80 percent of its toys in China. The company recalled some 21 million of its Chinese-made toys worldwide this year.

In October, one of its shareholders sued Mattel, accusing the company of failing to report serious defects in its toys.

Mattel said it was working with California's attorney general to improve toy safety.

"The use of paint with impermissible levels of lead by certain subcontractors was a clear violation of the company's quality and safety standards," Mattel said in a statement.