A 16-year-old boy arrested after a man was stabbed at the Notting Hill Carnival remained in custody today.
The boy was held in west London yesterday on suspicion of assault, Scotland Yard said.
The victim was stabbed towards the end of the event on Monday.
He was taken to a central London hospital where his condition was described as serious but stable after he was found with stab wounds to the stomach and hand shortly after 6pm in Ladbroke Grove, at the junction with Oxford Gardens.
Four other men held over the incident, three aged 20 and one 21, have been bailed to return to police in September, pending further inquiries.
Officers are keen to speak to a man seen in photographs attempting to prevent a suspect from leaving the scene by lifting his leg as an obstacle.
Europe's biggest street festival saw only a small number of isolated incidents amid an unprecedented security operation following the riots in London and other cities earlier this month.
Anyone who witnessed the incident or has information that may assist police was asked to call the incident room on 020 8246 9386, or Crimestoppers anonymously on 0800 555111.