Kidnappers have demanded $100,000 for the release of two U.S. missionaries seized on their way to church in Haiti's capital, a U.N. official said Thursday.

The captors initially sought $500,000 but lowered the ransom demand during negotiations with the FBI, said Leslie Dallemand, chief of the U.N. peacekeeping mission's anti-kidnapping unit.

An FBI spokeswoman in Miami, Judy Orihuela, declined to comment on the demand, saying the U.S. law enforcement agency doesn't discuss ransom details.

CountryWatch: Haiti

Tom Barron, a minister at The Mustard Seed church, and member William Eugene Seastrum were driving to church early Sunday when assailants stopped their car and dragged them out, Dallemand said. Both missionaries are from High Point, N.C.

"As far as I know, they're pretty healthy," Dallemand said. "The kidnappers didn't speak English. They made [one missionary] call his wife in North Carolina, and he did say he was OK."

Once relatively rare in Haiti, kidnappings became an almost daily occurrence after a bloody revolt toppled former president Jean-Bertrand Aristide in February 2004. Kidnappings leveled off following the February election of President Rene Preval, but the problem has worsened again in recent weeks.

U.N. officials say the kidnappings and other violence are aimed at destabilizing the new government, which took power in May.

On Wednesday, gunmen stopped dozens of cars traveling along a main road leading to the capital's airport and tried to seize the occupants, Dallemand said. At least two Haitians were reported kidnapped.

It's unclear how long Barron and Seastrum had been in Haiti. Dallemand said the two were staying at a hotel in the Port-au-Prince neighborhood of Delmas, where many kidnappings occur.

Dallemand said the FBI is working with U.N. and Haitian authorities to free the men, the latest foreign missionaries to be kidnapped.

Last month, Canadian missionary Ed Hughes was abducted from a rural town north of Port-au-Prince where he runs an orphanage. The 72-year-old was freed a week later after an undisclosed ransom was paid.

At least 29 people have been reported kidnapped in Haiti so far in July, about a third of them U.S. citizens, Dallemand said.

Last year, 43 Americans were kidnapped in Haiti, including three who were killed in attempted abductions, according to the U.S. Department of State's Bureau of Consular Affairs.