The Obama administration said on Tuesday that it would seek legislation requiring doctors to undergo training before being permitted to prescribe powerful painkillers like OxyContin, the most aggressive step taken by federal officials to control both the use and abuse of the drugs. In the last decade, the abuse of pain medications like OxyContin has remained at epidemic levels, and medical experts have expressed concern that the legitimate use of the drugs may also pose patient risks. For years, the question of whether doctors should be trained as a condition of prescribing such medications has been fiercely debated. Proponents of the training argue that it would help doctors better identify patients who would benefit from treatment with long-acting narcotics, and help them unmask patients feigning pain to get drugs they then abuse. Opponents say a training requirement will reduce the number of doctors prescribing pain drugs and hamper patient care.