EDMONTON — Animal rights activists say they may not file a threatened lawsuit against Edmonton if the city can provide clear proof that Lucy the elephant is too sick to be moved to a warm California sanctuary.

Zoocheck Canada and the People for the Ethical Treatment of Animals have written a letter to the city saying it has until Dec. 14 to provide documents and medical exam reports about the pachyderm's health.

The old, ailing elephant has been at the centre of a dispute between the city, which wants to keep Lucy at its zoo, and activists, including Hollywood celebrities such as William Shatner and Bob Barker, who say it is cruel to keep her there without other elephants for companionship.

Clayton Ruby, the lawyer representing PETA and Zoocheck, said if they agree with the city's experts about Lucy after reviewing the documents, the planned lawsuit will be dropped.

"We want to know what the basis is for their opinion," Ruby said from Toronto on Tuesday. "If we are satisfied by it, that is lovely. But we are unlikely to be satisfied by it."

Zoo officials announced last Friday that they had developed a treatment program for Lucy based on a report commissioned from Dr. James Oosterhuis, a veterinary consultant in San Diego.

The program is designed to deal with Lucy's breathing problems and arthritis. It also includes a special exercise program to help the 34-year-old Asian elephant lose weight. Oosterhuis has also suggested improvements to her indoor space.

PETA and Zoocheck contend the city is violating Alberta's Animal Protection Act by keeping an animal in distress.

The groups maintain that Lucy's pen at the zoo is too small, its concrete floor is hard on her feet and that Edmonton's long, cold winters deprive her of proper exercise. They argue that keeping a social animal alone without the company of other elephants amounts to solitary confinement.

"Every expert agrees that you cannot keep female elephants alone," Ruby said. "And they are planning on keeping her alone until she dies. And that is just cruel."

Ruby said even Oosterhuis has suggested that Lucy's pen isn't big enough and needs a rubber floor to take stress off of her feet.

Edmonton officials acknowledge receiving the PETA-Zoocheck letter, which is to be reviewed by the city's legal department.

Linda Cochrane, general manager of community services, said the city has provided plenty of information to groups interested in Lucy's welfare.

"We believe that we have been really quite open about what we are doing," Cochrane said. "Our main focus has been and will continue to be doing what is in the best interests of Lucy regardless of a threatened lawsuit."