A 13-year-old boy with Asperger's syndrome spent 11 days in the New York subway system after going missing following a school telling off, his mother has claimed.

Police found Francisco Hernandez Jr hiding out in a Coney Island station late last month having survived for almost two weeks on a diet of news stand confectionery and snacks.

His parents claim authorities were reluctant to make his case a priority because they are Mexican immigrants, but New York Police Department denied the claims.

Francisco is believed to have taken off on October 15 after he failed to complete a homework assignment and was told off for not concentrating in class. According to a report in the New York Times, the youngster walked eight blocks to the Bay Parkway station and boarded a train because it seemed like the best place to hide.

The 13-year-old suffers from Asperger's syndrome - a form of autism which makes it difficult for sufferers to communicate or interact with others. Fearing a scolding from his parents, Francisco removed the battery from his mobile phone. When he failed to return home from school, his mother Marisela Garcia scoured the nearby subway station - a previous incident had seen Francisco go missing for five hours on the network. After hours of searching, the police were called.

Over the next few days, officers interviewed teachers, classmates and distributed leaflets across the city showing the missing youngster's photograph. But despite their efforts he remained unnoticed on the busy subway system.

Francisco told the New York Times that he spent his days riding trains to the end destination before switching tracks and heading in the other direction. He lived on crisps, croissants and other snacks brought from the kiosks that litter the subway's stations. And despite thousands of flyers being distributed, no-one recognised or even talked to him, he claimed.

"Nobody really cares about the world and about people," he said.

He was eventually found on October 26. A transit officer was studying a sign with Francisco's photo on when he turned to see the boy sitting in a stationary carriage, it was reported. Apart from leg cramps, Francisco reported no physically ailments from his ordeal and is now back at school.

But his parents are now questioning why it took authorities so long to find the runaway on one of the world's busiest transport system.