BY FRANCES ROBLES

 WASHINGTON -- Elian Gonzalez's Cuban doctor left the United States in a huff Monday, saying the U.S. government refused to extend her stay.

 Her return to Havana surprised Immigration and Naturalization Service officials, who said they never told Dr. Caridad Ponce de Leon that she had to go home. The INS caught up with Ponce de Leon in Houston. Told she could remain another two weeks, the pediatrician said she would come back another time.

 ''I came here confident that I would be allowed to stay for as long as I was needed,'' she said. ''I have every confidence that this will be resolved and that I will be permitted to return.''

 Armed with a two-week visa, Ponce de Leon arrived in Washington, D.C., on April 27, as part of an entourage including Cuban children who came to keep Elian company. Her appearance was controversial from the start: U.S. Customs agents confiscated antibiotics and anti-depressants from her when she landed at Dulles International Airport.
 
 Her cache of medicines sparked criticisms that she was there to help drug and reprogram Elian.

 The doctor's visa originally expired Thursday, but the INS extended it until Monday to decide whether to permit her to stay longer.

 ''Juan Miguel made the argument that she contributed to a stable and familiar environment for Elian,'' said INS spokeswoman Maria Cardona. ''We're trying to figure out why she left. We made it clear that we were leaning toward extending it.''

 Ponce de Leon boarded a flight to Houston on Monday morning at Ronald Reagan National Airport, where she spoke to reporters. From there, she flew to Cancun. Juan Miguel's attorney, Greg Craig, tried to persuade her to stay, Cardona said.

 ''He tried to pull her back, but I don't think he did that in time,'' she said.

 Craig did not return a telephone message, nor did Cuban Interests Section spokesman Luis Fernandez.

 Should Ponce de Leon want to return, she will again have to tackle bureaucratic red tape: Even though the INS extended her current visa another two weeks, she cannot use it to reenter the country. To come back to Washington, she will have to apply in Havana for a fresh visa from the U.S. State Department.

 The government agency is still mulling the visa applications of Elian's seven grandparents, who seek to join him at the Maryland retreat where he is attending classes and getting reacquainted with his father.

 ''The recovery process is going very well,'' Ponce de Leon said of their reunion. ''Being in his customary environment, with his friends and teacher, has helped him a great deal. He is an incredible boy.''

 She said the boy and his father, Juan Miguel, seem very happy and spent Mother's Day penning a letter to Elian's late mother.

 Cuban television broadcast a telephone conversation between the boy and his grandparents Sunday, in which he blew kisses and told them about karate practice.

 ''Congratulations and kisses!'' Elian told his paternal grandmother, Mariela Quintana, as he blew kisses at her. Quintana wiped tears from her eyes.

 ''I sent you a letter, a postcard for Mother's Day,'' the boy told his maternal grandmother, Raquel Rodriguez. He said he made it himself and that it showed ''a big, red flower.''

 This story was supplemented by the Associated Press.

                     Copyright 2000 Miami Herald