Image caption San Francisco has already banned plastic bags and toys given away with fast food meals

The US city of San Francisco is weighing a proposal to ban the sale of pets within its borders.

Supporters say the ban would prevent needless suffering of animals, often bought on impulse by parents of children who soon tire of them.

The city's pet stores say the ban would put them out of business while doing nothing to prevent residents from purchasing pets elsewhere.

The move was proposed by an animal welfare advisory board.

But the city's legislative authority, the Board of Supervisors, has yet to take up the matter.

Human food exempted

The Humane Pet Acquisition Proposal was passed this month by the San Francisco Commission of Animal Control and Welfare, a panel of appointed commissioners that advises the Board of Supervisors.

Supporters say it is intended to crack down on large scale breeding of animals for profit, which they say lead to pets being kept in abusive, overcrowded conditions.

The ban would cover everything from rodents to reptiles, dogs, cats, fish and small birds.

It would also cover the sale of live animals such as mice used as food for pet snakes, but would exempt sales of live fish, lobsters and poultry destined for humans' dinner plates.