While peace edges closer in Colombia – ending a 40-year war between the government and leftwing Farc guerillas – so another war rages unabated: the appalling violence that surrounds mining and drilling for oil.

A remarkable survivor of these atrocities visited Britain this month for a tour of public meetings about his kidnap and torture, warning of the ravages of “extraction industries” in Latin America, and to consult his lawyers over a suit he has filed against BP for its alleged connections to the kidnappers.

Trade union activist Gilberto Torres was abducted by paramilitaries, apparently connected to the security arm of Ocensa – the joint venture company transporting BP’s oil, and in which it was an active member – in February 2002, and held for 42 days, during which time another man with whom he had been kidnapped was decapitated.

Torres was released after workers shut down pumping stations and refineries across Colombia in protest at his abduction. “If the companies were able to order my release,” he told the Observer, “how can they not have been somehow involved in my capture?” He now lives in exile, in fear for his life should he return home.

Torres’s case against BP does not allege its direct involvement in his kidnap. Instead it rests on the fact that at the time of his kidnap the company owned a 15.2% share in the Ocensa pipeline, which takes 650,000 barrels a day from his home state of Casanare, in central Colombia, to the Caribbean sea. Other stakeholders include TransCanada, Total and Triton. BP has been involved in the area since 1990, when it joined the rush to drill one of the biggest oil finds in the western hemisphere. Paramilitaries convicted of the kidnap have testified they were ordered by Ocensa to abduct Torres. Torres also points to known links between the rightwing paramilitaries and the Colombian army, which was also funded by BP to provide security for its operations.

Other actions BP currently faces over its operations in Colombia include a case brought by farmers who claim their fields and sources of water were contaminated, which nears a verdict, and a further suit lodged in July by Edita Guenis Arrigui, who claims her husband, Carlos Mesias Arrigui, was killed “by persons believed to have been responsible for security arrangements made by the defendants” – echoing Torres’s claim. Mesias was a woodcutter and community organiser whose activities, like those of Torres, affected BP’s operations. He had organised a village road block to pressurise BP into fixing the damaged road to their installation.

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Torres kicked off his tour by joining activists from the group BP-or-not-BP in a demonstration of impromptu theatre at the British Museum, in protest against its programme of exhibitions sponsored by the company. One upcoming event concerns Mexico’s Day of the Dead. “How very ironic,” says Torres, “that it’ll be paid for with money stained in blood.” The group is also preparing to contest BP’s plans for exploration in Mexico.

In an interview, Torres recalled how he had helped organise a strike in December 2001 in protest at the murder of fellow union activist Aury Sara. Three months later, he was kidnapped by men who included members of the rightwing paramilitary Self-Defence Forces of Casanare, driving an Ocensa security staff van. They beat Torres, then held him in a pit, chained and blindfolded. They shrieked at him for challenging the multinationals and left his wounds from the beating exposed to insects. After the total shutdown of oil production, he was released.

Torres began his legal action in Colombia, where it was delayed and fell foul of the statute of limitations. But an administrative tribunal ruled that his kidnap was a crime against humanity, necessitating the re-opening of his case. “We are gathering evidence in Colombia to get a verdict there, which can be the basis for the suit in London,” he said.

One paramilitary soldier has confessed to the kidnap and other crimes, and has testified of his involvement from jail. Of another four men also jailed, Torres said: “We have one more who we hope will agree to testify that they were instructed by the companies to kidnap me, and they have accused Ocensa directly.”

Torres said that his lawyers had applied to have the contracts regarding BP’s security arrangements, including its links to the army. “Our information is that at that time BP was in charge of security arrangements,” he said. BP denies this.

But the purposes of Torres’s tour, organised by War on Want, is also to “talk about the wider issue of human rights abuses in the extraction industry”. “Mining and drilling for oil have devastated Colombia. It is a Segundo Conquista – a second conquest [of the Americas]. Five hundred years ago, they came with conquistadors and mirrors. Now they come with oil drills and mines.

“These companies,” he continues, “are exploiting the resources without any regard to people’s needs. In areas into which the companies arrive, workers leave the land for jobs in oil drilling or mining, and crops go to waste. Workers can work a maximum contract of 28 days [after which] they remain around waiting for another contract, which leads to social disruption, crime, violence and prostitution.”

One mining town, Aguazul, with an initial population of only 50,000 “has swelled and now has the highest homicide rate per capita in Colombia – nothing to do with FARC and the army, it’s all because of oil extraction”. Torres adds: “In 1990, when BP and others arrived, the unions proposed a socially responsible and sustainable hydro-carbons plan. It was debated in parliament, and thrown out.”

Demobilised rightwing paramilitaries “came to protect the pipeline and the interests of the multinationals; when I was kidnapped they abused me for going against the companies’ interests. They are former fighters with the paramilitaries, but basically mercenaries – I don’t see this as part of the ideological war, they’ll work and kill for the highest bidder. They’re paid to harass, attack and kill anyone who questions the interests of the companies, who seeks to address environmental issues and the rights of workers or citizens in the area, and evictions from the area.” Amnesty International reports that some 11,000 people have already been displaced to make way for the Casanare pipeline.

“When I was held,” said Torres, “my captors complained that they were losing money by guarding me – they could be making between 1m and 46m pesos [£224-£10,320] for murders. And the number of such people available to protect corporate interests could double when Farc stops its war.”

Torres considers why the issue of abuses linked to the multinational extraction presence was not part of the peace process between Farc and the government, which recently broke through to a crucial final stage of talks hosted in Havana.“I think that had the issue of resources been subject to negotiation, the outside pressure of the corporate interests would have been so great, and the stakes so high, that the talks would have broken down.”

Torres said his personal life had been “torn apart by all this. I moved first to Madrid with my wife and son, but we were unable to afford to stay there with the economic crisis”. He moved to the Dominican Republic, “and my wife and son to Colombia, but I cannot go back – they’d kill me”. He spends his time preparing his case, and campaigning on behalf of Haitians being purged from their country.

Susan Willman, for Torres’s London lawyers Deighton Pierce Glynn, told the Observer: “Stricter laws are needed in the UK to deter multinationals like BP and G4S from investing in conflict zones like Colombia and Palestine where their presence will be associated with atrocities. At the very least, victims like Gilberto deserve access to a remedy in our courts, which is blocked by the lack of legal aid and huge fees.”

A spokesman for BP said: “While BP deplores what happened to Sr Torres, we refute any allegation that BP had any involvement with or knowledge of the incident or that BP in any way hired, worked with or encouraged paramilitary activities in Colombia during the time it had operations there … At the time of the incident affecting Sr Torres, BP was a minority shareholder in Ocensa and had no part in operating the pipeline”.

Ocensa said earlier this year that it “did not commission, order or pay for Gilberto Torres’s kidnapping” and had never been responsible for displacement, kidnapping or murder.