In a surprise delay, John Pistole, head of the Transportation Security Administration, said a change that would allow passengers to carry on small knives and some other formerly banned items (hockey sticks, golf clubs) had been delayed.

The rule change was to have gone into effect on Thursday.

A TSA spokesperson on Monday wrote in an email: "In order to accommodate further input from the Aviation Security Advisory Committee (ASAC), which includes representatives from the aviation community, passenger advocates, law enforcement experts and other stakeholders, TSA will temporarily delay implementation of changes to the Prohibited Items List, originally scheduled to go into effect April 25.

"This timing will enable TSA to incorporate the ASAC's feedback about the change to the Prohibited Items List and continue workforce training."

No date was given as to how long the policy would be delayed.

The TSA website had touted the upcoming changes in policy. On Monday it noted under its Prohibited Items List: “Changes Coming in the Near Future.” But information about the proposed changes was absent.

Flight attendant unions, more than 100 members of Congress and even families of 9/11 victims strongly opposed the policy change that would have allowed passengers to carry knives with blades smaller than 2.36 inches long and less than half an inch wide onto airplanes.

Rep. Janice Hahn (D-San Pedro) opposed the policy change and hadn't heard about Pistole's decision. "My only hope is that they are reconsidering this bad policy and, maybe in light of what we've experienced last week with the Boston bombings, they realize we're still under threat, bad people still want to hurt and kill Americans, and this is really not the time to go backward in safety policy," Hahn said.