NEW YORK — The U.N. agency that oversees aviation is pushing new guidelines for cargo security to counter al-Qaida’s new mail-bomb strategy, but is stopping short of calling for 100 percent screening of packages, as pilots and some U.S. lawmakers have urged.

The proposed changes by the International Civil Aviation Organization concentrate on “supply-chain security,” or checking outbound shipments before they even reach the airport.

Governments are increasingly worried about cargo security as the holiday season swells the number of packages moving around the world.

In October, militants based in Yemen tried to blow up cargo jets with 38 bombs hidden in printer cartridges. The bombs were stopped only because of a tip from Saudi intelligence officials, Transportation Security Administration chief John Pistole told Congress.

Since August, the United States has been screening all cargo loaded onto passenger planes that take off from U.S. airports. But there is no such requirement for cargo-only planes, or for flights coming from abroad.

Last week, a magazine published by al-Qaida urged members to launch more mail bomb attacks, calling them a “good bargain.”