Investigations into the drugging of preschool children in Taiwan have sparked widespread alarm on the island.

Teachers at a kindergarten in New Taipei City have been accused of sedating students with cough syrups containing drugs like phenobarbital and benzodiazepines.

Police have been investigating for weeks and say it's not clear why the children were fed the addictive syrups.

But the scandal has sparked family protests outside government buildings.

Hundreds joined a demonstration in New Taipei City on Sunday calling for greater transparency from the police investigation, with many criticising authorities for their lack of public disclosure.

On Monday, a separate case also emerged concerning a medical practice in the southern city of Kaohsiung, on the other end of the island.

The local health department there found four doctors guilty of misconduct and improper use of phenobarbital on about 20 children. They were ordered to suspend their practice for six months, and were fined 1.4m Taiwanese dollars (£35,989, $46,121).

Amid growing public concern, Taipei City Hospital has also begun offering free blood tests for preschool children to check for traces of sedatives.

The measures come after the scandal first emerged in May, when parents at a private preschool in New Taipei City accused staff of feeding their children "unknown drugs".

Mike, a father of a five-year-old child, told BBC Chinese that parents had noticed what appeared to be withdrawal symptoms in their children over the long Lunar New Year holiday period in February.

"Some parents found their children, over the vacation, had become irritable, restless and screamed when sleeping, and even cried out with leg cramps," he said.

After speaking to the children, parents learnt that their teachers had fed them an "unknown potion". Complaints were filed with police in April and May.

Following more complaints from parents in June, local authorities launched an investigation, and found at least eight children with trace amounts of phenobarbital and benzodiazepines - a class of psychoactive drugs - in their system.

The kindergarten at the centre of the controversy, a franchise of the Kid Castle Educational Institute, was ordered to shut down on 12 June. Its directors have been fined 150,000 Taiwanese dollars(£3,800 $4,872).

The principal and five teachers were arrested and questioned by police but have since been released on bail. A criminal investigation is underway.

Local media reported that the staff said the parents had consented to a list of medicine provided by the school but some parents in response questioned the medicines used by the school.

A Taiwanese pharmacist told local media that, although rare, some cough and gastrointestinal medicine contain phenobarbital.

Drugs containing phenobarbital are mostly used in the treatment of epilepsy and or used as surgical anaesthesia, and are difficult to obtain.

Benzodiazepines are a class of depressant drugs most commonly used to treat severe anxiety.

The drugs are highly addictive, and overdose may lead to drowsiness and shortness of breath.