A two-metre long boa constrictor is on the loose in Fredericton, say police.

A Colombian red-tailed boa constrictor went missing on Sunday from a home in the area of Hanson and Beckwith streets, which is near the University of New Brunswick, police said in a Facebook post.

The owner, who wouldn't give his name, told CBC he's had the snake for three months. He says he bought the six-year-old snake named Venus from a pet store.

It is believed the snake, which weighs about 13 kilograms, escaped from its cage on Sunday around 7 p.m. The owner says he keeps it in a glass case, but didn't lock the sliding door.

Jake Sisk lives in the apartment above the snake.

"My buddy lives downstairs and I heard some people talking about the snake being missing so I just ran down, started looking for the snake with my buddy Marcus. Unluckily we didn't find it last night, so we had to call animal control," he said.

Despite assurances from the police that the snake is not dangerous, nearby residents like Dave Clark are taking no chances.

He covered access points to his home.

Clark says he's seen the owner out walking with the snake on his shoulders.

"It bothers me to see it. I'm not really a snake person," he said.

The owner told CBC News that he stopped taking the snake out once he realised it was against a city bylaw.

"If you come across the snake, please use caution, keep a safe distance and contact the Fredericton Police at 460-2300," the Facebook post states.

New Brunswick SPCA, Department of Natural Resources, animal control and city bylaw officials responded to the scene.

The Colombian red-tailed boa is an unregulated species that does not require any authorization to own, according to the police.