The Foreign Office has advised Britons travelling to Paris to "exercise caution in public places". Security has been stepped up in the French capital, and security checks are expected to take longer than usual.
Here's the latest advice from the train, ferry and flight operators for people planning to travel.
Driving to France
French borders are not closed, but border checks have been reinstated
Ferry services from Dover are running as normal
Eurostar advises that all services are running normally
A free exchange is being offered for passengers who planned to travel today but now don't want to.
It says all passengers should check their website before setting off
Flights to Paris airports are operating normally
There are extra security checks at all airports across the country which British Airways advises may cause delays to flights
British Airways says anyone due to fly to Paris on Saturday can delay their flight to any day within the next two weeks or rebook to an alternative destination
Easyjet advises that anyone travelling on their planes in the next 48 hours can cancel and get a refund
Flybe has said that any customer travelling on Saturday or Sunday who no longer wishes to do so can rebook to a later date to any alternative destination, or obtain a credit note for future travel.
Passengers are advised to contact Customer Services
The Foreign Office has its latest advice here
It says people concerned about relatives or friends should call 020 7008 0000