In the first case of its kind, the farmers claim environmental damage caused by BP’s oil pipeline threatens their livelihoods.

More than 100 Colombian small farmers are taking on oil giant BP in the UK high court on Wednesday in one of the largest cases in environmental legal history.

The farmers say the British company Equion Energia, formerly BP Exploration (Colombia) Ltd or BPXC, was negligent in the construction of the Ocensa oil pipeline in the mid-1990s. It ran through their properties and, they claim, caused serious damage to their land, crops and animals. If the claim is successful, it could open the way for similar claims by other communities in developing countries who say they have been adversely affected by oil pipelines.

The four-month trial will be the first time BP has faced a UK court over its actions overseas and the first time compensation for environmental damage to privately owned land, caused by a UK oil company, has been litigated in the UK. BP says it is vigorously defending the case, arguing that it took significant steps to compensate farmers for laying the pipeline on their land and to ensure that no harm was caused.

A British judge will rule on whether BP breached agreements with the farmers and was negligent in causing environmental damage when building the pipeline.

The farmers’ lawyers say they did not fully understand the contracts signed with BPXC and did not receive full and fair compensation for environmental damage under the agreements. The claims will be argued with reference to contractual and extra contractual liability under Colombian law.

A group of Colombian farmers previously reached an out-of-court settlement with BP for alleged environmental damage caused by the pipeline. But this time BP has changed its approach and decided to fight the claims in court.

The hearing, in the UK’s technology and construction court, comes a month after a US judge ruled that BP was “grossly negligent” in the runup to the Gulf of Mexico oil disaster, in which millions of gallons of crude were spilled into the sea. BP could face fines of up to $17.6bn (£11bn) for the spill.

Some of the farmers have come to London to give evidence. Rogelio Velez Montoya, 54, has a 47-hectare (116-acre) farm in Segovia, a region with a long history of conflict. He grows yucca, corn, rice and beans, and keeps cattle, hens and pigs.

“Our water supply has been damaged by sedimentation since the pipeline was laid, and I have lost cattle,” he says. “I can no longer keep pigs or chickens because there is not enough water for them. The reason why we have travelled so far is because we have hope and faith that the high court in London will deliver justice to us.”

Rodrigo de Jesus Mesa, 63, has a 38-hectare farm mostly used for traditional cattle rearing. He also grows crops and fruit, and keeps hens. “After the pipeline was laid our water sources filled up with mud,” he said. “It made farming very difficult – but I can’t even sell the farm because of the pipeline. When people find out I have an oil pipeline running through my farm they no longer want to buy it … We hope that all the farmers who have brought this case together will get justice.”

The farmers say the pipeline caused severe soil erosion and sedimentation of fields and water sources, reduced vegetation coverage and areas for pasture, and blocked water sources, significantly reducing the productivity of their farms.

Shubhaa Srinivasan,the partner at Leigh Day representing the farmers, says: “At last the farmers are going to have a chance to tell their stories and to have their case decided. We feel it is really important that big companies are held to account for the way in which they undertake their activities abroad – especially when those activities take place in remote corners of faraway places, out of the public gaze.”

A BP spokesman says: “The Ocensa pipeline project in Colombia involved significant steps being taken at the time of construction to engage with local communities, make appropriate compensation payments and ensure that the land that the pipeline traversed suffered no material damage. BP believes that these measures were effective and that the construction of the pipeline was carried out to a high standard. BP is confident in this legal position and believes it is appropriate for the case to be defended vigorously.”

The pipeline was laid in the 1990s by BP in partnership with Colombia’s national oil company and four other multinational companies after BP discovered more crude oil in the Cusiana-Cupiagua oil fields. BPXC entered into contracts with the farmers to lay the pipeline through their land.