Female recruits to the US Navy will not have to endure short hair cuts when they start boot camp under an experiment launched by the military's top brass.

Officers said Thursday the rule requiring a female recruit's hair be trimmed above the collar is being suspended for a trial period of three months, partly to aid recruiting and partly in response to complaints that new sailors needed to learn how to groom longer hair styles before they go to sea.

Female recruits have to have their hair chopped short during their first two to three months in the navy, but the other branches of the US military do not make the same requirement of their female recruits, said Commander Chris Servello, spokesman for the navy's chief of personnel.

"We're the only service to make it mandatory for women to cut their hair," Servello told AFP, and it was possible the practice could mean losing some promising recruits.

"All things being equal, a young woman may choose to go somewhere else if she doesn't want to have to cut her hair," he said.

Some sailors in the fleet had suggested trying the change so that junior female sailors are "better prepared" when they arrive on a ship, instead of having to learn how to wear their hair longer during their first deployment, he said.

The pilot program, which will run through March 2015, "comes after receiving fleet feedback that junior sailors and officers are not taught proper grooming standards with longer hair," the navy said in a statement.

But female recruits could still opt for the short style -- to "the lower edge of the uniform collar" -- if they wanted, it said.

All the military services have detailed rules about grooming and hair styles, but Pentagon chief Chuck Hagel called for a review of the regulations after new standards upset some female soldiers in the army, particularly African-American troops.

The young female sailors can check out 19 different approved hairstyles in an official website (http://www.navy.mil/ah_online/um/femalehair.html). The parameters do not allow for big hair or anything too flamboyant.

"Lopsided and extremely asymmetrical hairstyles are not authorized," according to the hair grooming policy regulations.

Male recruits as well may get a reprieve from the storied crew cut, which generations of sailors have received upon signing up for the navy.

Naval officers said the service is considering easing the mandatory head shave for the men entering boot camp.