Image caption Knives have not been allowed in the cabin since the 9/11 attacks - and these types will remain banned

The US transport safety authority has said it will allow some small pocket knives aboard US flights for the first time since the 9/11 attacks.

From 25 April, passengers may bring blades shorter than 2.36in (6cm) and narrower than 0.5in in plane cabins.

Fixed blades, razors and box cutters will still be forbidden, the Transport Security Administration (TSA) said.

The change has been criticised by flight attendants, who say it will put passengers and crew at risk.

Also under the new policy, billiard cues, ski poles, and lacrosse and hockey sticks will be allowed in aeroplane cabins in carry-on luggage.

The TSA said the new rules would bring the US into line with international guidelines and offer a better experience for passengers.

"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," a TSA spokesman told the Reuters news agency.

But the Flight Attendants Union Coalition called the move "poor and short-sighted".

"As the last line of defence 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 group said in a statement.