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
Over the next 24 hours we are going to see snow and ice across many parts, although it is looking calmer from Sunday onwards.
A young grey seal found in a farmer's field on Monday is making progress say RSPCA staff. He's thought to have a head injury.
The UK economy, boosted by the inclusion of the sex and drugs industry in the calculations, is now the world's fifth largest, but only just.