It is "impossible" that Frida Kahlo painted some 1,000 pieces presented by two antique dealers as her work, the daughter of the artist's husband, Diego Rivera, told a press conference in the Mexican capital.

Kahlo was never a prolific artist, Guadalupe Rivera said, responding to a statement by dealers Carlos Noyola and Leticia Fernandez that the Mexican Attorney General's Office supported their claims about the authenticity of the paintings.

Mexico's central bank and the Diego Rivera and Frida Kahlo Museums Trust had asked the AG's office to consider possible criminal charges.

After finding no evidence of forgery, prosecutors dropped the matter.

"It's no good talking about a legal victory since there was no lawsuit. Because of a loophole in criminal law, there is no way to sanction those who reproduce works of art without authentication or permission from their creators or owners, Guadalupe Rivera said.

With no charges pending, Noyola and Fernandez said their projects include founding a museum for the purported Kahlo works and possibly creating a traveling exhibition.

The dealers are committing "a very serious offense against morality, against honesty, and are practicing deception in the name of artists whose works are considered artistic monuments," Guadalupe Rivera said.

She did not, however, express concern about the possibility of the works being put up for sale at auction, since, she says, she has been advised that they have already been rejected by the big international auction houses, given their doubtful provenance.

Guadalupe Rivera urged legislators to pass laws that categorize as crimes the forgery and sale of works of questionable authenticity.

Experts on Kahlo's works, such as museum curator James Oles and Teresa del Conde, director of the Esthetic Research Institute of the National Autonomous University of Mexico, were also unwilling to guarantee the dealers' collection as genuine.

Some 470 works by Kahlo (1907-1954), whose self-portraits and poems have made her one of the great icons of Mexican culture, have been duly authenticated and most of them are in museums.