The top U.N. human-rights official said Friday she welcomed President Bush's opposition to executing mentally retarded people and expressed hope that it could be a "turning point" in the debate.

"I have written to President Bush, in the light of this statement, urging him to intervene in several cases where persons with mental disabilities are awaiting execution in the United States," said Mary Robinson, U.N. high commissioner for human rights.

Robinson said she had asked Bush to make his views known to courts considering such cases and to governors considering signing legislation to ban the practice. His successor as Texas governor has just such a bill on his desk.

"The world would welcome American leadership on this very important issue," she said. "The human rights of people with mental disabilities have been widely neglected in virtually in every country."

Bush made his remark in an interview with European journalists Monday shortly before Oklahoma City bomber Timothy McVeigh was executed by lethal injection.

"We should never execute anybody who is retarded," Bush said. "Our court system protects people who don't understand the nature of the crime they committed."

Robinson, who opposes the death penalty, said she hoped Bush's remark could "mark a turning point, not only with respect to the right to life itself, but with respect to the other human rights of people with mental disabilities who are disproportionately represented in prisons throughout the world."

Texas Gov. Rick Perry must decide by Sunday whether to sign a bill to ban the execution of killers who are mentally retarded. State lawmakers passed the legislation last month. Perry has said he has problems with the bill.

Bush's brother, Florida Gov. Jeb Bush, signed a bill this week making Florida the 15th state to ban the execution of retarded defendants.