US mandatory budget cuts could lead to a doubling of the time it takes for people to clear customs and immigration at major US airports, the head of the US Department of Homeland Security has warned.

Speaking at the 22nd AVSEC World conference in New York Tuesday, DHS Secretary Janet Napolitano described the budget cuts—referred to in the US as sequestration—as “a rolling stone that picks up speed as it goes downhill.”

“Over the next weeks and months, average times to clear customs could increase up to 50%. Peak wait times are now already too long at about two hours and they could grow to four hours. It’s just doing the math,” Napolitano said.

If Congress continues to fail to agree on a budget, then the across-the-board, $85 billion federal cuts that came into effect March 1 will also continue and government agencies will not be able to pay overtime, replace posts and will have to implement staff furloughs.

Sequestration was heavily criticized by many conference speakers. US Aerospace Industries Association president and CEO Marion Blakey said it was a “spiral that gets worse and worse.” JetBlue Airways president and CEO Dave Barger said it was “a totally unacceptable way to run a business, let alone a country.” IATA DG and CEO Tony Tyler added that it was unacceptable for the airline industry to be impacted. “Airlines pay their way for security,” he said.