The South American country is being torn apart by fighting between right- wing paramilitary groups, left-wing revolutionaries and state-controlled forces.
The Government's first set of immigration statistics, revealed today, will show that thousands of Colombians have fled to seek asylum in Britain. Nearly all have been refused entry.
Yesterday the Government faced further problems over immigration as the Campsfield detention centre in Oxfordshire erupted into violence.
Fires were started in the dormitories and library as 50 inmates, all awaiting immigration clearance, went on the rampage. More than 100 police officers, many in riot gear, were called to quell the disturbance.
The Government is struggling with a backlog of 53,000 asylum applications and 22,000 appeals from rejected applicants.
But it is the clampdown by immigration officials on Colombians which has particularly concerned organisations working with refugees who believe innocent people have been put at risk of assassination.
By May, asylum applications from Colombia were up 500 per cent on 1996, when there were a record 1,005 applicants.
Next month the Refugee Council will produce a report, Caught in the Crossfire, which will claim that officials have turned down many asylum applications because of a lack of understanding of human rights issues in Colombia.
Tony Kay, who researched the report, said: "They have not got a proper appreciation of the human rights violations going on on the ground because the situation is changing so quickly."
The report will show that members of M19, once a left-wing guerrilla group but now a legitimate political party, have been refused asylum on the grounds that their legal status means they can now expect protection from the Colombian government. Similar assurances were given in refusing applications from members of the left-wing coalition Union Patriotica (UP), which has lost 3,500 activists to political assassination.
But Juan-Carlos Lema, of the London-based Colombian support group Open Channels, said: "The fact that M19 became a political party does not mean they are not at risk. A lot of people want to have revenge and the government is too weak to give protection."
Claude Moraes, of the Joint Council for the Welfare of Immigrants, said that despite Labour pledges of reform, a "general culture of disbelief" remained among the Home Office officials who deal with asylum-seekers. The criticisms will concern Labour after its pledges to uphold human rights.
Amnesty International says government forces have frequently co-operated with right-wing paramilitaries, who are responsible for a dramatic escalation of "torture, political killings and disappearances".
More than 1,000 civilians were extrajudicially executed by the security forces and paramilitary groups last year. This week protesters demonstrated outside the Colombian embassy in Knightsbridge over the country's human rights record.
The increase in violence over the past year has coincided with an exodus of refugees to Britain and elsewhere. But within a month of the election, the Government clamped down on the influx by introducing a new visa requirement for all Colombians coming to Britain.
In a speech that was unreported by the press, Mike O'Brien, the immigration minister, warned of the "increasing and alarming" numbers of Colombians making "unfounded" claims for asylum.
Since the change in the law, monthly asylum applications from Colombia have tumbled from nearly 250 to just 15.
Refugee support groups said that people fleeing persecution were often among the 1 million displaced Colombians and were unable to produce evidence of a home and a job, which is usually required for a visa.
Some members of the British Colombian community, numbering around 50,000 and concentrated in London, fear they are being stigmatised over police fears that Colombian drugs cartels are targetting Britain.
In an attempt to improve the situation, the Refugee Council has held a series of private meetings with Home Office officials in recent weeks, aimed at making the treatment of Colombians more "fair and efficient".