A lethal brew of oil and blood

In the complex, often murky world of oil exploration, British Petroleum's presence in Colombia looks to be just another case of a Western multinational prospecting for the benefit of itself and the host government in the face of the vociferous objections of local environmental and human rights activists.

But the stakes here are far higher, and now threaten to drag the oil company into one of the world's largest and so far under-reported civil wars. Two weeks ago Colombia's endemic violence spread to Britain when Colombian inmates at the Campsfield detention centre in Oxfordshire went on the rampage.

For the UK government, facing a five-fold increase since last year in the number of Colombian refugees seeking asylum and a lengthening backlog of applications, it was a stark warning of the volatility of this particular South American political brew.

For BP, the refugee problem is very bad news: the greater the exodus from Colombia, the more the spotlight will fall on the reasons for the company's presence there. Even though these are mostly economic rather than political, its role will inevitably be questioned. Already, by its presence in Colombia, BP stands accused of complicity in human rights abuses and environmental damage.

The root of BP's problems is that, to fulfil its contract with the Colombian government to locate and extract oil in the north-east province of Casanare, between the capital Bogota and the Venezuelan border, it relies for its security not just on the expertise of ex-SAS consultants - from the London- based company DSL - but on local police and a division of the national army. Though retained and funded by the company, these troops - many of them conscripts on national service - have proved a frequent and visible liability. Human rights campaigners in Colombia and the UK have levelled charges of kidnapping, torture and murder against them.

Some campaigners have gone further. Leaflets from the London-based Coalition Against BP in Colombia have carried slogans such as "BP Murders for Oil" and said that the company "sponsors" paramilitary death squads.

Of course, for the company to do either would be a PR disaster, but there is strong evidence that army elements are affiliated to the paramilitaries, often using them as surrogates to intimidate or wipe out "opponents".

In Colombia it is seldom easy to know who is in the right and who in the wrong: mud sticks, and few can avoid it. This works both ways: most of those threatened by the paramilitaries may well claim to support legitimate trade unions and political parties, but there are many who, covertly or otherwise, owe allegiance to the guerrillas whose "left-wing" struggle against the government has been poisoned by their own human rights abuses.

Having begun operations in Casanare in the early 1990s and since created one of the world's biggest onshore oil fields, with estimated reserves of $40bn (pounds 25bn), BP must be in for the long haul. So far its activities have impinged upon the sphere of influence of FARC, the largest of the country's guerrilla groups, but it has attracted more particular attention from the second largest, the National Liberation Army (ELN). The ELN is allied to the third largest, the dissident wing of the Popular Liberation Army (EPL). With other groups, these three operate under the umbrella of the Coordinadora Guerillera Simon Bolivar (CGSB).

Though Maoist in ideology, the ELN specialises in kidnapping and extorting money from the oil industry. By these and other means it is said to have amassed huge wealth, with investments in hotels, coca plantations and foreign shares.

At the last local elections the ELN also got seven of its candidates elected as mayors in towns in Casanare, securing its share of the oil royalties paid by BP and channelled via central government to the municipalities.

FARC, having first become implicated in the hard-drug trade by levying "grammage" - a toll by weight on traffickers wishing to pass through its territory - has moved intensively into coca growing and processing. One of its cocaine "fortresses", destroyed by the police and army in the south of the country, was reported to have employed 1,000 people and produced a staggering 5,000kg of cocaine "base" a week. The guerrillas are also said to have moved into poppy farming and the even more lucrative heroin trade. Some drugs are bartered for weapons, but the profits are still huge.

Of Colombia's legal exports oil has become the biggest, worth $1.6bn last year. To block its flow and destabilise the government, the guerrillas have escalated the war by launching direct assaults on the industry. This year they have struck about 40 times at the pipeline from Occidental's main field, causing severe environmental damage. Soldiers guarding repair teams have been ambushed, with 34 killed early last month in two incidents. In Casanare six local policemen have been killed guarding BP's oil rigs in the past two years.

After one attack, the ELN forced radio stations to broadcast a communique saying that all workers and facilities of BP Exploration (BPE) in east Casanare were "military objectives".

BP has fared worse in the war of words than Occidental, a US oil company. On the premise that anything weakening BP gives Washington more leverage in Bogota over drugs, this may suit broader US interests.

But BP may have been singled out because it refuses to pay the guerrillas direct protection money. John Doust, BPE's regional president, has said BP is the victim of a "smear" campaign in the western media, orchestrated by the ELN. This claim, first reported from other sources in the Independent on Sunday in June, has to some extent been supported. (See accompanying story).

BP looks unlikely to get off the hook, especially as it plans to move into remote areas known to be cocaine and heroin centres. Not only does it threaten the guerrillas' territory and income, but so do the activities of the paramilitary groups allied to its military protectors. First formed to protect farmers and landowners, and said to have become the biggest gangsters in the drugs trade, the paramilitaries have been seizing land and pushing suspected guerrillas towards areas BP intends to explore.

For the British government, the prospect would seem to be one of lengthening refugee queues - and for BP, one of deepening embarrassment.