The U.N. Refugee Agency says it is extremely concerned about the worsening situation of thousands of people in Colombia who have been forced to flee their homes in recent weeks because of intensified fighting.

UNHCR spokesman Kris Janowski says that over the past few weeks, thousands of people, mainly women and children, have been on the move. He says most of these people are living under dire conditions in a situation of acute vulnerability.

He says they are living in shantytowns or other makeshift accommodations and are mainly dependent on irregular government handouts. He says people are being forced from their homes by threats from illegal armed groups or by violent clashes between combatants.

"We have also seen problems in the border areas of neighboring countries, which are affected by the intensification of the conflict in Colombia," Mr. Janowski said. "There have been a number of violent incidents, including killings and abductions attributed to illegal armed groups."

Mr. Janowski says fighting by illegal armed groups is destabilizing Colombia's borders with Venezuela and Ecuador. The United Nations estimates more than two million people in Colombia have been internally displaced since 1995, this out of a population of 40 million.

A spokeswoman for the International Organization for Migration, Niurka Pineiro, says instability in the country also is creating what she describes as a serious brain drain. She says some of Colombia?s brightest and most skilled people have left the country for good.

"We have come up with an official figure of 1.2 million Colombians who have left the country legally, never to return, most of them," she said. "And another 500,000 - this is an estimate, not an official figure - of people who have left with the assistance of smugglers or traffickers."

Ms. Pineiro says more than four million people, or about 10 percent of Colombia's population, have been directly affected by the country's worsening situation.

Colombia's newly elected president, Alvaro Uribe, has vowed to put an end to the fighting that has plagued Colombia for decades. He has enacted stringent measures to end the conflict, but so far, to little effect.