WASHINGTON (Reuters) - American attitudes have changed and the "don't ask, don't tell" policy toward gays serving in the U.S. military should be reviewed, former Joint Chiefs of Staff chairman Colin Powell said on Sunday.

President Barack Obama favors overturning the policy, which bars gay troops from serving openly in the military. U.S. Defense Secretary Robert Gates has asked military lawyers to look at ways to make the law more flexible, hailed by gay rights groups as a "seismic political shift".

"The policy and the law that came about in 1993, I think, was correct for the time," Powell said on CNN's State of the Union.

"Sixteen years have now gone by, and I think a lot has changed with respect to attitudes within our country, and therefore I think this is a policy and a law that should be reviewed." he added.

Current Chiefs of Staff Chairman Admiral Mike Mullen, the United States' highest ranking officer, said the military will continue to carry out the policy until it is changed.

"It is very clear what President Obama's intent here is, he intends to see this law changed and my advice ... is that I think we need to move in a measured way," Mullen said.

"At a time when we're fighting two conflicts there is a great deal of pressure on our forces and their families," he added.

(Reporting by Lesley Wroughton; Editing by Sandra Maler)