WASHINGTON (Reuters) - The Transportation Security Administration said on Tuesday that travelers can soon bring small pocket knives on board airplanes for the first time since the September 11 attacks, sparking outrage from flight attendants who said the decision would endanger passengers and crew.

The TSA said that effective April 25, it would allow knives with blades that are 2.36 inches or less in length and less than 1/2 inch wide. Other items that will be allowed on board again as part of a passenger's carry-on luggage include billiard cues, ski poles, hockey sticks and lacrosse sticks.

Items that had been prohibited like razors, box cutters or knives with a fixed blade are still not allowed on board.

TSA spokesman David Castelveter said the decision was made to bring U.S. regulations more in line with International Civil Aviation Organization standards and would also help provide a better experience for travelers.

"This is part of an overall Risk-Based Security approach, which allows Transportation Security officers to better focus their efforts on finding higher-threat items such as explosives," he said.

The Flight Attendants Union Coalition, which represents nearly 90,000 flight attendants from carriers across the country, called it a "poor and shortsighted decision" by the TSA.

"As the last line of defense in the cabin and key aviation partners, we believe that these proposed changes will further endanger the lives of all flight attendants and the passengers we work so hard to keep safe and secure," the coalition said in a statement.

Castelveter said the TSA had implemented a number of safety measures, including reinforced cockpit doors, allowing some pilots to be armed and federal air marshals on board airplanes. He said those measures would help ensure safety of the passengers and crew.

At Ronald Reagan Washington National Airport in Washington, travelers reacted to the change with alarm.

"I would say, what were you thinking? Because it's ludicrous to think of allowing knives on a plane," said Deborah Debare. "They are as dangerous as guns."

Another traveler, David Veeder, said that when it came to knives and blades, even small instruments could pose a danger.

"I'd prefer they had nothing," he said.

After the September 11, 2001 hijacked airliner attacks on New York and Washington, the government imposed strict rules for what could be carried on board an aircraft, some of which differed from what other countries allowed.