The government is preparing to issue new rules that will make it substantially easier for veterans who have been found to have post-traumatic stress disorder to receive disability benefits for the illness, a change that could affect hundreds of thousands of veterans from the wars in Iraq, Afghanistan and Vietnam.

The regulations from the Department of Veterans Affairs, which will take effect as early as Monday and cost as much as $5 billion over several years according to congressional analysts, will eliminate a requirement that veterans document specific events like bomb blasts, firefights or mortar attacks that might have caused PTSD, an illness characterized by emotional numbness, irritability and flashbacks.

For decades, veterans have complained that finding such records was extremely time consuming and sometimes impossible. And in the wars in Iraq and Afghanistan, veterans groups assert that the current rules discriminate against tens of thousands of service members - many of them women - who did not serve in combat but still suffered traumatic experiences.

Under the new rule, which applies to veterans of all wars, the department will grant compensation to those with PTSD if they can simply show that they served in a war zone and in a job consistent with the events that they say caused their conditions. They would not have to prove, for instance, that they came under fire, served in a front-line unit or saw a friend killed.

The new rule would also allow compensation for service members who had good reason to fear traumatic events, known as stressors, even if they did not actually experience them.

There are concerns that the change will open the door to a flood of fraudulent claims. But supporters of the rule say the veterans department will still review all claims and thus be able to weed out the baseless ones.

Though widely applauded by veterans' groups, the new rule is generating criticism from some quarters because of its cost. Some mental health experts also believe it will lead to economic dependency among younger veterans whose conditions might be treatable.

Disability benefits include free physical and mental health care and monthly checks ranging from a few hundred dollars to more than $2,000, depending on the severity of the condition.