Coca-Cola's bottling plants in Colombia used rightwing death squads to terrorise workers and prevent the organisation of unions, it was alleged in a Miami court yesterday.

The US union United Steelworkers is suing Coca-Cola on behalf of the Colombian union Sinaltrainal for what the lawsuit describes as "the systematic intimidation, kidnapping, detention and murder" of workers in Colombian plants.

Sinaltrainal claims that five of its members working in Coca-Cola bottling plants have been killed since 1994.

Coca-Cola denied any responsibility for the alleged atrocities yesterday, saying the company did not own the bottling plants, which operated under contract.

But union lawyers argued that the world's best-known soft drinks company closely controlled the operations of its contractors and was well aware of the brutal intimidation of workers in the bottling factories.

The case has focused attention on frequent complaints by critics of globalisation that the process of contracting out work to developing countries allows corporations to shirk their responsibilities for safeguarding the basic rights of their workers.

The lawsuit details a litany of assassinations and terror which, it claims, were carried out by rightwing paramilitary groups on behalf of the management of the Colombian bottling plants.

It points to the murder of a unionmember working at a Coca-Cola bottling plant in Monertia, Cordoba province, on June 21 this year. Oscar Polo was shot to death as he was walking in the street with his youngest daughter. At the time, he had been involved in negotiations with the management over proposals to provide security to trade unionists under threat.

The lawsuit also gives details of alleged paramilitary operations at the Bebidas y Alimentos bottling plant in the town of Carepa, which operates under contract for Coca-Cola.

Two Sinaltrainal members, Jose David and Luis Granado, were murdered in 1994. The union lawsuit alleges that the killings were carried out by paramilitary forces, which then presented the rest of the workforce with an ultimatum either to resign from the union or flee Carepa.

"The management of Bebidas y Alimentos permitted these paramilitary forces to appear within the plant to deliver this message to union members and leaders," the lawsuit alleges.

Sinaltrainal tried to rebuild its presence at the Carepa plant in 1995, but within a year the death squads had killed a new union board member, Isidro Gil.

Coca-Cola distanced itself from its bottling plants yesterday. "The Coca-Cola company does not own or operate any bottling plants in Colombia," a corporate spokesman, Rafael Fernandez said.

"We deny any wrongdoing regarding human rights or any other unlawful activities in Colombia or anywhere else in the world."

Daniel Kovalik, a US steelworkers' lawyer, said that Coca-Cola had stepped in to curb human rights abuses in Guatemala after three union leaders had been killed in the 1980s. That intervention showed that the company could stop the killings if it chose to, he argued.