The doctors find themselves here despite a shift in U.S. policy, announced in August, that allowed Cuban medical personnel working abroad to come to the United States once they passed routine background checks.

Most of the defecting doctors who fled to Colombia have been waiting as long as six months for a response, according to an advocacy group in Miami and several doctors who spoke to The Associated Press. At least two have been rejected by U.S. officials.

Jorge Toledo, a 39-year-old physician, and his wife, ophthalmologist Leticia Viamonte, were told in a Dec. 27 letter that their request to enter the United States under the Cuban Medical Professional Parole program was denied. The Associated Press obtained a copy of the letter. The decision cannot be appealed.

Joanna Gonzalez, a Homeland Security spokeswoman in Washington, declined to comment on the Cuban doctors. But she said that any applicants under the program "must pass a background check," like others seeking to enter the United States. The U.S. Embassy in Bogota declined commeting on specific asylum cases.

Colombia's Foreign Ministry said the government has not decided whether to grant refugee status to Cuban doctors who have applied for asylum here in recent years. The ministry said there were 45 such cases.

Julio Cesar Alfonso, president of the Miami-based relief organization Solidarity Without Borders, said his three-year-old organization has provided economic and legal assistance to 38 Cuban doctors trying to leave Colombia. He estimates the overall number of doctors who have defected and are living here could exceed 100.

"There's no explanation for the delay _ these applications should've taken a maximum two or three months," said Alfonso, a Cuban-trained physician who immigrated to the United States seven years ago.

Cuban officials last year said they had 31,000 doctors serving in humanitarian missions in 68 countries around the world _ a major point of pride for the communist nation.

They said more than 20,000 are on loan to Venezuela and another 1,700 are based inBolivia, whose leftist President Evo Morales is a frequent visitor to Havana.

More than 500 doctors are believed to have fled the two missions in recent years, most in Venezuela, Alfonso said.

Like Toledo and Viamonte, most asylum-seeking Cuban doctors are just scraping by because they are unable to work in Colombia without refugee status.

The couple said they applied for refugee status at the U.S. Embassy on Aug. 11, the same day the new program was announced in Washington. Only one of the seven other doctors who applied that same day has so far been granted entry to the U.S., they said.

Toledo and Viamonte said they sneaked into Colombia in December 2005. Cuban authorities assigned them to Venezuela in mid-2003.

Like other Cuban doctors here, Toledo and Viamonte live in fear of being deported toCuba.

So far, Alfonso said, Colombia's government _ Washington's closest ally in Latin America _ has granted Cuban doctors who defect safe-conduct passes that are renewable every three months.

Toledo fought back tears and anger as he described his disappointment at being rejected from the refugee program.

"We didn't ask for this law _ we thought it was a miracle when this program was announced because it was so explicit and clear," he said. "Not even for a second did we think we or anyone else would be turned back."