The group hoped to achieve its aims using “war, anything”, according to whistleblower Robbie Mullen.
The disillusioned former National Action member scuppered a plan to murder Labour MP Rosie Cooper when he reported it to campaigning charity Hope Not Hate, the Old Bailey was told.
Jack Renshaw, of Skelmersdale, Lancashire, has admitted preparing acts of terrorism by buying a knife to kill the politician as well as threatening to kill a police officer.
Last July, the 23-year-old was allegedly given the blessing of National Action leader Christopher Lythgoe, 32, who told him not to “f*** it up”.
Lythgoe, from Warrington, denies giving Renshaw permission to murder the West Lancashire MP on behalf of National Action.
The pair, along with Garron Helm, 24, of Seaforth, Merseyside; Matthew Hankinson, 24, of Newton-le-Willows, Merseyside; and Andrew Clarke, 33, and Michal Trubini, 35, both of Warrington, are on trial at the Old Bailey.
All six have denied being members of National Action, which was banned in December 2016 for supporting the murder of Labour MP Jo Cox.
It means that being a member of or inviting support for the organisation is a criminal offence and carries a maximum sentence of 10 years in prison.
Whistleblower Mr Mullen, from Widnes, Cheshire, who joined National Action in 2015, told jurors the group stood for “the free white man” and was against “everything – Jews, blacks, Asians, every non-white”.
Prosecutor Duncan Atkinson QC asked what National Action hoped to achieve, to which Mr Mullen replied: “Wipe them out by any means necessary. War, anything.”
He implicated all the defendants in the extreme right-wing organisation, saying they continued to be involved with it after the ban.
Mr Atkinson said this week: “This case concerns these defendants and their support for, involvement in and membership of the proscribed racist neo-Nazi group National Action.”
Jurors have been shown National Action propaganda videos of demonstrations across England and Scotland in which men wore skull masks, waved banners and made Nazi salutes.
The trial continues.