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
Queens Parks Rangers defender Rio Ferdinand has announced his retirement from football after his wife's recent death.
A promising start to the weekend - fine and bright for most of us but showers will crop up across northern Scotland.
A war veteran who was burgled said he is overwhelmed after thousands of pounds were raised for him by people he had never met.