A bill to require manufacturers to install "kill switches" in smartphones is close to passing out of the state legislature.

Senator Mark Leno's proposal has cleared the Assembly and now returns to the Senate for final amendments.

The Democrat from San Francisco says the legislation responds to an exploding crime problem, but Republicans argue it's a burden to phone companies and leaves state standards out of sync with the rest of the nation.

The technology to deactivate phones won't be mandated until the middle of next year and, after a push from industry interests.

The bill does not apply to tablets.