The incident happened near Hauz Khas when Manoj and another inmate were being taken back to the Tihar jail from a court in Saket.
An under-trial man was killed in a fight that broke out between two inmates on a prison van on its way to Delhi's Tihar jail, police said on Saturday.
The man identified as Manoj, 28, had been lodged in the Tihar prison since 2005.
He had been charged with attempt to murder.
The incident happened near Hauz Khas when Manoj and another inmate were being taken back to the Tihar jail from a court in Saket.