Travel insurance premiums and holiday costs will go up, following the alleged outbreak of food poisoning at a hotel in Torremolinos.
Customers are suing eight tour operators, including Thomsons and JMC after 1,500 people fell ill last November and this summer.
Euclidian's account executive for tour operators liability, Gary Armstrong, said:
"Even if there is no liability on the tour operators, the cost of defending an action of this size could be substantial. This will, in due course, have to be reflected in premiums and eventually holiday costs."
Armstrong said his initial investigations suggested it would be difficult to establish any liability on the tour operators involved.
"But I must stress that we still have a considerable amount of investigation to complete," he said.
Irwin Mitchell partner Clive Garner said the company has been inundated with inquiries regarding the bout of food poisoning at the Beach Club Hotel,Torremolinos.
He said: "The claims are expected to be millions of pounds."