Richard Galpin, Jakarta – A senior police official in Indonesia has confirmed reports that 30 people demonstrating on Wednesday against the re-election of the governor of Jakarta were poisoned with cyanide.

Many others were injured when the police fired rubber bullets and used water canon to disperse one of the largest demonstrations seen in the capital since the downfall of the former President, Abdurrahman Wahid, more than a year ago.

The head of the forensic laboratory at national police headquarters in Jakarta said cyanide had been found in food that had been handed out to the demonstrators at the height of the protest on Wednesday.

Thirty people were taken to hospital after collapsing and vomiting, but most have now recovered and been discharged.

The police official said it is easy to get hold of cyanide as it is found in rat poison.

A student leader told the BBC an unknown person had brought five large bags of food, which was distributed to those taking part in the demonstration. He accused supporters of the Jakarta governor of being responsible.

Despite the large demonstration the governor, retired Lieutenant General Sutiyoso, was re-elected for another five-year term by city councillors. Voting allegations He is an extremely controversial figure and deeply unpopular with the majority of the population in the capital who had wanted him replaced.

Many were particularly angered by his failure to tackle massive flooding in the city at the beginning of the year which left more than 30 people dead and hundreds of thousands homeless.

There have been allegations that Wednesday's vote in the city council was manipulated, particularly when it was announced that councillors had to hand-write their choice for governor on the ballot papers, making it easier to identify who had voted for which candidate. The allegations have been denied.