BOGOTA, Colombia— Every six hours, a kidnapping is reported in Colombia. Every four days a kidnapping is reported in Rio de Janeiro. But these two places, notorious though they may be, are just the tip of an iceberg of abductions looming over Latin America.

Huge income disparities, inefficient police forces, and near-total impunity for kidnappers are transforming Latin America into the world's top region for ransom kidnapping. The threat is inhibiting investment in the region and is forcing wealthy Latin Americans to use private guards, high walls and armored cars for protection.

A victims' group estimates that over the last three years $400 million has been paid in ransom in Colombia alone. But the toll goes far beyond ransom payments.

"Fear of kidnapping has cost the country many economic growth points, thousands of jobs, millions of dollars," Portafolio, a Colombian business newspaper, wrote in a recent editorial. "Who is going to invest and work to the maximum with such a high risk? It is absurd that one of the consequences of business success is to increase the probabilities of losing life, freedom, health and family peace. We cannot get out of underdevelopment with such a sword of Damocles."

Brian M. Jenkins, a deputy chairman of Kroll Associates, a New York-based company that specializes in executive security, estimates that last year Latin America had more than 6,000 kidnappings -- 4,000 in Colombia, 800 each in Mexico and Brazil, 200 each in Ecuador and Venezuela, and 100 each in Guatemala and Peru.

Latin American governments' official figures for the number of kidnappings are much lower, because of underreporting by victims' families and reluctance by governments to harm their images. "Governments seeking foreign investment and tourism have little incentive to publicize their kidnapping problems," Mr. Jenkins said.

In contrast, he said, the United States has fewer than a dozen kidnappings for ransom every year. There is concern, however, that Mexico's economic collapse could increase kidnappings there this year, and perhaps spill over into cross-border abductions.

Referring to an estimated $30 million ransom paid last June to free Alfredo Harp Helu, chairman of Mexico's largest bank, Banamex, Mr. Jenkins said that "in Mexico, the Banamex kidnapping was inspirational to criminals."

But the biggest problem remains Colombia, he said, adding, "Latin America is now the No. 1 region for kidnapping, and Colombia is the No. 1 country in the world." The list of hostages in Colombia includes nine Americans, the largest such group in the world.

Of the region's major kidnapping centers, Colombia is the only one in which political abductions play a major role. Pais Libre, a Colombian kidnapping victims' group, studied last year's kidnappings and concluded that guerrillas carried out at least half.

Peace talks with Colombian guerrillas are scheduled to resume this year after a three-year hiatus. Some Colombians speculate that the guerrillas are collecting American hostages to strengthen their hand at the negotiating table.

The guerrillas generally deny that they finance their operations through kidnappings.

"We have always been against kidnappings -- we have ordered a few political detentions," Jorge Briceno, the Revolutionary Armed Forces' spokesman for peace talks, told a Bogota newspaper, El Espectador, in February. "But we have nothing to do with economic kidnappings."

But a different voice was heard recently from the guerrillas when Pais Libre played a tape recording that it said was a radio conversation last August between a guerrilla commander and Wilma Garzon, the mother of a 31-year-old farm manager kidnapped on Oct. 30, 1993.

"The guy's already dead so we are going to charge you 10 million pesos to deliver his corpse," the man identified as the guerrilla commander said. "If you don't want it that way, we'll throw him in a hole somewhere."

Mrs. Garzon paid the money -- about $14,000 at the time -- but never received her son's body.

"The going price for an oil executive is $200,000," said Guy Squires, who has been working here for over a year to coordinate efforts to free five of the American hostages, missionaries for New Tribes Mission, a Florida-based Protestant evangelical group.

Guerrillas for the Revolutionary Armed Forces of Colombia, the nation's largest guerrilla group, have demanded $5 million for the release of three of the missionaries, who were seized in Panama in 1993 and later brought into Colombia.

"We are a mission and we cannot afford to pay ransoms," said Mr. Squires, who was last in contact with the guerrillas by radio a year ago.

Mr. Squires and friends of other Americans kidnapped in Colombia complain of the low level of interest by the United States.

"We were passed off to aides and not allowed to speak to Senators," Mr. Squires said of his trips to Washington with wives of several kidnapped missionaries.

His concern is echoed by Eugene Harter, a writer who is a friend of Thomas R. Hargrove, a journalist who is one of the nine hostages.