A poisonous Egyptian cobra remained on the loose at the Bronx Zoo today — and jittery visitors griped that they hadn’t been told about it before entering.

The 20-inch-long snake, dubbed Cobra-dini by zoo-goers, escaped from its enclosure at the Reptile House on Saturday and hasn’t been seen since.

But “we are confident that the snake is secure within the Reptile House,” said zoo director Jim Breheny in a statement. “When the snake gets hungry or thirsty, it will start to move around the building. Once that happens, it will be our best opportunity to recover it.”

The brownish cobra, with a uniquely large, broad head, is among the most venomous reptiles on the planet — its poison can kill a person in fewer than 15 minutes.

Sylvia Cruz, of The Bronx, who was at the zoo with her 8-year-old daughter, Melissa, griped: “They aren’t doing a good job of alerting people about it. We went to the Reptile House and found out it was closed. It’s really scary and makes me want to leave the zoo before something bad happens.”