One case affected more than 500 and was the biggest outbreak yet under President Prabowo Subianto's flagship program.

From January, when the program was launched, up to August, over 4,000 children have been hit by food poisoning after consuming the meals, according to think tank the Institute for Development of Economics and Finance (INDEF), raising questions on oversight.

In West Java, 569 students from five schools in Garut experienced nausea and vomiting on Wednesday after consuming chicken and rice provided by one free meals kitchen a day earlier, Nurdin Yana, the secretary of Garut regency, told Reuters.

"As of Friday, ten students are still being treated at the hospital and others have recovered," Yana said. Initially, about 30 students had to be hospitalised, while the rest were treated at home, he added.

The local government will increase surveillance of the kitchen that provided the meals, Yana said, adding the program would not be halted but, instead, students would be given more basic food, such as bread, milk, boiled eggs and fruit for now.

Another mass food poisoning case linked to the program occurred on Wednesday in the Banggai Islands, Central Sulawesi, affecting 277 students, the National Nutrition Agency (BGN), which oversees the programme, said in a statement, adding that meal distribution in the area was temporarily halted.

Presidential spokesperson Prasetyo Hadi said on Friday that the government apologized for the "re-occurrence of cases in several areas that are, of course, not what we had hoped for or intentional."

Questions have been raised about standards and oversight of the program, which has expanded rapidly to reach over 20 million recipients, with an ambitious goal of reaching 83 million by year-end and a budget of Rp 171 trillion (US$10.32 billion).

The budget for the program will be doubled next year.