Washington ? U.S. and European officials signed an agreement Friday for sharing information on airline passengers, saying the new policy addresses concerns about privacy.

During a signing ceremony, Homeland Security Secretary Tom Ridge, European Union Ambassador Gunter Burghardt and Irish Ambassador Noel Fahey, representing the EU presidency, said the deal was key to fighting terrorism.

“A global enemy requires a global response,” Ridge said. “It is an essential security measure that allows us to link information about known terrorists and serious criminals.”

The agreement, which takes effect immediately and is to last 3 1/2 years, gives U.S. authorities access to information about passengers on flights flying to or from the 25 European Union countries. The information will be checked against U.S. databases to determine if any travelers are terrorist threats.

U.S. officials already have had access to the information under an interim program that began in March 2003, but many in Europe said that agreement did not provide adequate privacy protection. Supporters of the deal signed on Friday say it protects privacy because it limits the information that can be transferred. It also restricts use of the information to combatting terrorism and serious crimes, and allows U.S. officials to keep it for only 3 1/2 years.

David Sobel, general counsel for the Electronic Privacy Information Center, a critic of the agreement, said none of the assurances were binding.

“There is so much secrecy surrounding the government’s handling of passenger data that it will be virtually impossible to monitor the use of the information,” Sobel said.

The data include credit card numbers and contact information such as phone numbers and addresses. Some sensitive items, such as meal requests that could indicate a passenger’s race or religion, will either not be transferred or will be filtered out by U.S. authorities, the officials said.