The arrests for 'conspiracy to prepare acts of terrorism' focussed on a network allegedly based in the south-west city of Toulouse.
The men, three of them tried in their absence, were part of terrorist network that trained in Afghanistan and reportedly planned attacks in France.
Germany's Angela Merkel to discuss with Francois Hollande a European solution to avoid emails and other information passing through the US.
The four, aged between 22 and 35, were arrested in the Paris suburb of Vitry-sur-Seine following an investigation that started in mid-2012.
French police have dismantled what officials called a "huge" Albanian heroin-trafficking network, making 39 arrests in the eastern town of Mulhouse.
Company says the origin of a problem that left 26 million customers unable to make calls or send text messages was a software problem.
France may abandon plans for a major extension of its high-speed train network as the new left-wing government strives to shrink its huge debt.