WASHINGTON (AP) – The government Wednesday announced new security requirements for air cargo that include criminal background checks for more than 100,000 airline and freight workers and screeners to check packages delivered to airport ticket counters.

The Transportation Security Administration said it will also use more bomb-sniffing dogs to screen freight that’s shipped by plane and that it will soon finish hiring 300 new air cargo inspectors, which Congress included in the agency’s budget this year.

“We have set a solid foundation for a major segment of the transportation network,” said TSA chief Kip Hawley. “In the time-sensitive and dynamic air cargo industry, a layered security approach is essential to thwarting would-be terrorists.”

Cargo pilots have long complained that the government focuses most of its efforts on protecting passenger airliners from terrorist attacks, leaving cargo planes vulnerable. They point out that cargo planes could also be seized by terrorists and used as weapons.

Some lawmakers have criticized the Bush administration for screening airline passengers and their luggage but not inspecting the cargo that’s carried on the same plane.

The air freight industry, though, doesn’t want commerce to be impeded.

The TSA’s long-awaited plan – it was originally proposed in November 2004 – includes new regulations for restricting access to sections of airports used for loading and unloading cargo.

It also requires the employees of more than 4,000 freight forwarders – agents who accept packages and arrange shipment – to attend security training courses designed by the TSA.

The TSA has relied on a “Known Shipper” program to make sure bombs or weapons don’t make their way onto passenger planes. Air cargo companies must register with the government and be approved by the TSA before they’re allowed to send cargo on passenger airliners.

The TSA said it will consolidate 4,000 Known Shipper lists into one so it can keep closer track of companies that ship cargo on passenger planes.

The agency said that in recent weeks it banned three companies from sending cargo on passenger aircraft.