The men, aged 39 and 55, were picked up by officers from Scotland Yard's counter terrorism command.
Both are being held under the Extradition Act after being arrested at a residential address in west London.
More top news
A controversial plan to introduce visa checks in Melbourne has been cancelled following backlash from the city's community.
Former archbishop Jozef Wesolowski has died ahead of facing paedophilia charges in the Vatican.
The makers of the latest Star Wars film have released more teaser footage of the upcoming blockbuster.