Veterans of the 1991 Gulf War who have complained that something in the region made them sick to this day have new evidence backing them up.

A federal panel of scientific experts said that the condition sometimes called Gulf War syndrome or Gulf War illness is a real problem that affects one in four of the 697,000 military members who served in the conflict.

The report, commissioned by Congress and released through Boston University, blamed exposure to chemicals such as pesticides and a drug meant to protect against nerve gas.

The symptoms of the illness generally include fatigue, memory loss, pain, headaches and difficulty sleeping. Some veterans also complain of immune-system problems. It can also entail digestive problems, respiratory symptoms and skin rashes.

"The extensive body of scientific research now available consistently indicates that Gulf War illness is real, that it is the result of neurotoxic exposures during Gulf War deployment, and that few veterans have recovered or substantially improved with time," the report says.

The report says the illness differs from stress-related problems usually seen after battle.

"Studies consistently indicate that Gulf War illness is not the result of combat or other stressors, and that Gulf War veterans have lower rates of posttraumatic stress disorder than veterans of other wars," the committee wrote.

The authors said that the government should spend more on improving health for the veterans.

They also said that other chemicals could be a factor, including exposure to nerve agents and smoke from oil-well fires.