Driven by worsening economic conditions and political violence, growing numbers of Colombians are fleeing their country in an exodus that U.S. officials fear may turn into an immigration crisis.

The U.S. Embassy in Bogota has been swamped with requests for visitor's visas and is turning down record numbers of applicants because of suspicions they intend to stay in the United States permanently. "There's a potential for mass departures," a federal immigration official said. "Planes are booked solid. Everyone's trying to get out."

Colombian American groups and other Latino activists are urging the federal government to accommodate the fleeing Colombians by offering temporary refuge to those who reach the United States and by softening the criteria for granting political asylum. In several U.S. cities last week, thousands of Colombians and their supporters held rallies to demand "temporary protected status," which allows people from war-torn or disaster-ravaged countries to live and work in the United States for up to 18 months.

But the State Department says it has no plans to recommend temporary protected status for Colombians, and the Immigration and Naturalization Service says it cannot bend the asylum rules to cover people affected by "generalized" strife or economic conditions, rather than persecution aimed specifically at them.

In a letter to President Clinton last week, Rep. Lincoln Diaz-Balart (R), whose South Florida district includes thousands of Colombians, attributed an "exodus of refugees" from Colombia to "escalating guerrilla violence" and "rampant kidnapping." He said asylum approval rates for Colombians are "exceptionally low" and called for immediate action "to correct this disparity."

The INS said the asylum approval rates in recent years have been comparable to those for other nationalities and have risen sharply since 1997. In the first six months of this fiscal year, 35 percent of Colombian asylum applications were approved, the same as the worldwide average for that period, INS officials said.

From January through April, an estimated 65,000 Colombians left the country, many bound for the United States, and Colombian officials estimate that up to 300,000 others could leave by the end of the year. Nearly 1 million people have been driven from their homes by fighting between the army and leftist rebels, a conflict that has dragged on for three decades but now seems to have shifted to the rebels' favor. Authorities in neighboring Venezuela, Ecuador and Panama have expressed concern about a swelling flow of refugees across their borders.

In Bogota, the U.S. Embassy reports that visa applications this summer have jumped to 50,000 a month, double the rate of a year ago and far more than consular officers can process. The embassy's appointments calendar for interviews with visa applicants is fully booked until January, a State Department official said.

The long visa lines in front of the U.S. and other embassies reflect growing disillusionment among Colombia's middle class, officials said. While the guerrilla war is an enduring factor, much of the impetus for the flight appears to come from the country's deteriorating economy. Since the early 1990s, Colombia's foreign debt and its unemployment rate have doubled, reaching nearly $34 billion and 20 percent respectively. After years of steady growth, the economy shrank by nearly 6 percent in the first quarter of this year.

In demonstrations on Colombia's independence day last Tuesday in Miami, Washington, Houston, Atlanta, Chicago and New York, organizers called on the administration and Congress to pay more attention to the country's problems and provide refuge for the thousands of Colombians who have arrived here. According to Juan Carlos Zapata, head of the Colombian American Service Association in Miami, an estimated 15,000 Colombian families have arrived or overstayed their visas in South Florida in the past few months.

Fewer than 15,000 Colombians a year are admitted as legal immigrants, the INS says. It estimates that about 60,000 live in the United States illegally.