The present invention relates to a high-voltage circuit-breaker including a casing that is filled with a dielectric gas and that contains a first arcing contact and a second arcing contact, which arcing contacts are mounted to move in opposite directions from an open position to a closed position and vice versa, the first contact being secured by means of a ring to a tube mounted to slide in a support portion electrically connected to a terminal. Said ring is made of an insulating material, the first contact is extended by a rod that is in alignment with the contact, which rod is disposed on the side of the first contact that is further from the second contact, and is connected to a resistance, and said rod carries a switching member organized to connect said rod directly to said support portion during closure.