PARIS (AP) — French Prime Minister Manuel Valls says it's "intolerable" that violent protesters smashed windows of operating rooms at a renowned children's hospital on the fringes of a labor demonstration.

Valls, visiting the Necker Hospital on Wednesday, denounced what he called unprecedented violence against a hospital, and urged unions to halt their months of protest.

Largely peaceful demonstrations against legislation weakening rigid French labor protections have routinely degenerated into violence by small groups.

On Tuesday, masked troublemakers hurled paving stones and other projectiles at businesses and the Necker Hospital. Some 30 police officers and protesters were injured.

Necker is among the world's leading children's hospitals, and patients come from around the world for advanced surgery and treatment for cancer and other diseases.