ALBANY, N.Y. (AP) — Gov. Andrew Cuomo vetoed legislation that would block plans to move a child psychiatric center to the campus of an adult mental health facility in Buffalo, upsetting opponents who wanted the two facilities to remain separate.

The bill rejected by Cuomo on Wednesday passed the Legislature by a unanimous vote earlier this year. The measure would have stopped the move and kept the Western New York Children's Psychiatric Center at its current site in West Seneca, a suburban community south of Buffalo.

Current plans call for the 46-bed children's center to be relocated to the campus of the much-larger Buffalo Psychiatric Center, which provides out-patient services in addition to more than 150 in-patient beds for adults.

Opponents say the relocation will put children at risk by placing them near adults with significant mental illnesses. They also point to the current facility's park-like setting and say there's no reason to move it.

"'Bigger and better' is not a justifiable reason to close a facility that has saved the lives of vulnerable children," said Assemblyman Michael Kearns, a West Seneca Democrat who was one of the main supporters of efforts to keep the existing children's center open. "We don't need hindsight to see that moving this facility, to the same campus as adult psychiatric patients, downtown in a busy urban environment, will be a colossal mistake."

Cuomo, a Democrat, said concerns about patient safety are unfounded. He noted that the two facilities will be "completely separate" and that adult patients will have no access to young patients. He said the state has already invested $5.1 million in the move, which was announced four years ago. The existing children's center, he said, is in need of "substantial repair."

"I cannot support a bill that would have such a negative impact on children and families in need of mental health services and directly compromises four years of work that will demonstrably provide better and more accessible care for children," Cuomo said in an explanation of his veto.

Kearns is urging the Legislature to return to Albany for a special session to override Cuomo's veto. Lawmakers will kick off the 2018 session Jan. 3 and a special session in December is considered unlikely.

The relocation plan calls for keeping the West Seneca center open until all existing patients are discharged, while new patients will be admitted to the new facility once it opens in a few years.