(Adds share move, claim details)
May 28 (Reuters) - London-listed shares in oil and gas company Ithaca Energy fell by as much as 18 percent after the Calgary-based firm said it had received a legal claim regarding its Greater Stella Area oil field in the North Sea.
The company, which denied any wrongdoing, said a statement of claim had been lodged complaining it had misrepresented the schedule for completing modifications at a floating production facility.
Ithaca said in February that modifications to the "FPF-1" facility, being carried out by UK oil services firm Petrofac Ltd , would not be completed until 2016.
Ithaca noted that the statement of claim had come from a law firm that advertises itself as undertaking investor law suits.
Toronto-based law firm Morganti Legal said in March that it was investigating whether Ithaca's views about the completion date of FPF-1 were "overly optimistic".
Morganti and Petrofac were not immediately available for comment.
Ithaca's London-listed shares fell as low as 42.5 pence before recovering to 49.49 pence, down 5.3 percent by 0820 GMT. (Reporting By Mamidipudi Soumithri in Bengaluru; Editing by Anupama Dwivedi and Rodney Joyce)