Tens of thousands of Ivory Coast nationals who allege that toxic waste dumped by commodities trader Trafigura made them ill are poised for landmark compensation after a bitter legal battle that sounds a warning to other multinationals with British operations.

Leigh Day, the law firm bringing the damages action, said it was “optimistic” its clients would agree to an undisclosed global deal offered by Trafigura to end an English High Court case in which the company had fought hard to avoid any suggestion of liability.