Washington (UP) - Attorney General Francis Biddle Thursday urged that congress consider legislation revoking the citizenship of American-born citizens of Japanese descent who have professed loyalty to Japan.

Biddle appeared before a house Dies subcommittee investigating riots at the Tulelake, Calif., camp of the War Relocation authority. He said such legislation "might very possibly be the solution to the whole problem of American citizens who are loyal to Japan."

"Do you mean it would be constitutional to revoke the citizenship of a person born in this country?" asked Rep. Herman Eberharter, D., Pa.

"Oh, absolutely," Biddle replied. "There would be no question of the constitutionality."

Biddle said the problem of the 110,000 Japanese-Americans and Japanese excluded from the Pacific coast was one of "defense and law."

He said he believed there was no question of the legality of the order excluding Japanese from the west coast, but added there was "grave doubt" of the constitutionality of interning American citizens - not enemy aliens - after they were once removed from the coastal area.

Previously Director Dillon S. Myer of the War Relocation authority testified there were no Pearl Harbor day celebrations in any of the 10 Japanese relocation centers in this country, although "frankly we had considered it possible that pro-Japan internees would try to stage something."