A six-month-old baby girl died after crawling off her sleeping parent's market stall and falling into a bucket of diluted acid.

The horrific accident happened at the family's vegetable stall at Libertad Public Market in Bacolod City, the capital of Negros Occidental province in the Philippines.

The baby's mother, whose name has not been released, told police she and her husband had decided to sleep at their stall as they were too tired to go home.

The baby had been asleep on the stall while her mum, dad and two-year-old brother slept nearby.

They awoke to find the baby girl had somehow fallen into a bucket of water mixed with oxalic acid, a simple but strong solution often used to remove rust from metal.

The family believe the little girl woke up and managed to crawl to the edge of the stall before falling into the bucket.

They rushed the baby to the nearby Corazon Locsin Montelibano Memorial Regional Hospital but she was declared dead on arrival.

Marinel Palacios, the girl's aunt, urged people not to blame the baby's parents saying they took good care of her despite the busy demands of work.

Police say they are withholding the names and addresses of the rest of the family, at their request.

Police Captain Elmer Bonilla said the incident was being investigated but said the family's explanation for the death of the baby was regarded as plausible.

Authorities are visiting stallholders at the market to warn other parents of the dangers of failing to keep a close watch on young children and babies.