Six people held in connection with a foiled terrorist attack on a train travelling between Amsterdam and Paris have been released without charge, police said.

Gunman Ayoub El-Khazzani, 26, was overpowered by fellow passengers after they noticed him loading a weapon on the high-speed Thalys service last August.

He was charged with attempted murder of a terrorist nature and remanded in custody.

Six others who were held for questioning on Monday have now been released, a spokesman for the Belgian federal prosecutor said.