The move has been described by sources as the civil service “prepping” for all possibilities.
The revelation came as further Government splits emerged over whether Britain should quit the EU without an agreement as Defence Minister Tobias Ellwood broke ranks and insisted a no deal scenario must be ruled out.
A Downing Street spokesperson said: “Respecting the referendum decision means leaving the EU.
“The PM has said that there will be disruption in the event of no deal, but as a responsible Government we are taking the appropriate steps to minimise this disruption and ensure the country is prepared.”
In other measures the Government sought to extend working hours for MPs in order to get Brexit legislation through the Commons before the scheduled EU withdrawal date of March 29.
Responding to news the Government was looking at the possibility of a martial law scenario, Labour MP and Best for Britain campaign supporter, David Lammy said: “This is a full-blown crisis.
“The Government is recklessly drawing up plans for a colossal act of self-harm.
“Through continuing on the path to Brexit, despite having achieved no consensus on a deal in Parliament, the Government is preparing to declare war on itself.
“The idea that the Government has any mandate for this catastrophic scenario is ludicrous.
“The Leave campaign promised a stable new trading relationship with the EU after Brexit, not total isolation and soldiers in our airports.”
Despite Prime Minister Theresa May refusing to take the prospect of a no deal off the table, Mr Ellwood wrote in the Sunday Times: “It is now time to rule out the very possibility of no deal.
“It is wrong for Government and business to invest any more time and money in a no deal outcome which will make us poorer, weaker and smaller in the eyes of the world.”
Also writing in the Sunday Times, Commons Leader Andrea Leadsom branded bids by some backbench MPs to kill no deal as an option via a series of Commons amendments on Tuesday as a “thinly veiled attempt to stop Brexit”.
In a bid to try and ensure Brexit legislation gets through the Commons and Lords in time for the planned March exit, Parliament’s February recess is to be cancelled, and MPs will be made to start earlier and finish later on sitting days.
The move comes after the Commons Leader suggested that leaving the EU might need to be delayed by “a couple of weeks” in order to get all the legislation through.
Reports that the Number 10 chief of staff Gavin Barwell had criticised the role of the Prime Minister’s husband Philip May in Brexit discussions were dismissed as “utter bunkum” by a Downing street spokesperson.