The Met said Tuesday’s arrests were made under the Police and Criminal Evidence Act (PACE) and were both part of the same terror probe.
A spokesman for the force told the Standard that the arrests were “right-wing terrorism-related”.
The men were taken to a south London police station where they are still being questioned.
Police added searches of the homes they were found in are currently ongoing.
The arrests come after Michael Nugent, who shared explosives and firearms manuals while expressing his far-right views online, was convicted of terrorism offences.
Using different personas, he expressed racist views and a hatred of ethnic minorities while also sharing terrorist-related documents.
Nugent also shared manuals on how to make explosives and homemade firearms and told group members about how to deliver bombs in Amazon packages.
At Kingston Crown Court on Thursday, 13 May, Nugent pleaded guilty to five counts of dissemination of terrorist publications (contrary to section 2 of the Terrorism Act 2006); and 11 counts of possession of a document containing information likely to be useful to a person preparing or committing an act of terrorism (contrary to section 58 of the Terrorism Act 2000).
He is due to be sentenced on 23 June 2021.