Trade talks between the UK and European Union are continuing in Brussels with one day to go until a deadline imposed by the two sides.
The leaders of both parties have warned they are unlikely to reach a post-Brexit trade deal by Sunday.
On Friday, Boris Johnson chaired a "stock-take" on the UK's preparedness for a no-deal scenario.
Meanwhile, the Ministry of Defence (MoD) said four Royal Navy patrol boats are ready to protect UK fishing waters.
The Sunday deadline was set by Mr Johnson and European Commission President Ursula von der Leyen after the pair met in Brussels on Wednesday, after months of talks failed to achieve an agreement.
Mr Johnson said the EU needed to make a "big change" over the main sticking points on fishing rights and business competition rules, while Mrs von der Leyen said no deal was the most probable end to "difficult" talks.
The EU has rejected Mr Johnson's request to bypass the European Commission and speak directly to French President Emmanuel Macron and Germany's Angela Merkel about the unresolved issues.
According to EU officials, he was told discussions could only take place through the bloc's chief negotiator, Michel Barnier, who is meeting with his UK equivalent in Brussels.
If a trade deal is not reached and ratified by both sides by 31 December, the UK and EU could impose taxes - tariffs - on each other's goods.
This could lead to higher prices for some goods, among other changes.
- Brexit happened but rules didn't change at once: The UK left the European Union on 31 January 2020, but leaders needed time to negotiate a deal for life afterwards - they got 11 months.
- Talks are happening: The UK and the EU have until 31 December 2020 to agree a trade deal as well as other things, such as fishing rights.
- If there is no deal: Border checks and taxes will be introduced for goods travelling between the UK and the EU. But deal or no deal, we will still see changes.
A major sticking point in negotiations has been access to UK fishing waters, with the EU warning that without access to UK waters for its fleets, UK fishermen will no longer get special access to EU markets to sell their goods.
The MoD has said it has conducted "extensive planning and preparation" to ensure it is ready for a range of scenarios at the end of the transition period, including having 14,000 personnel on standby to support the government over the winter with the EU transition.
It said four offshore patrol boats will be available to monitor UK waters and added that it would have "robust enforcement measures in place to protect the UK's rights as an independent coastal state".
An expansion of powers for the Royal Navy Police, enabling officers to potentially board foreign boats and arrest those breaking the law, is one proposal in the MoD's no-deal contingency planning, a spokesman confirmed.
Gun boat 'threat'
Admiral Lord West, former chief of naval staff, told BBC Radio 4's Today programme it was "entirely appropriate" for the Royal Navy to protect UK waters, although he said there would need to be parliamentary authority to allow officers to board foreign ships.
But Tobias Ellwood, Conservative chairman of the Commons Defence Committee, called the threat of using Royal Navy gunboats to patrol UK waters in a no-deal outcome "irresponsible".
"This isn't Elizabethan times anymore, this is global Britain - we need to be raising the bar much higher than this," he told Today.
According to the MoD's website, three River Class patrol ships with a crew of 45 sailors already work "at least 275 days a year at sea enforcing British and European fisheries law".
BBC economics editor Faisal Islam said the government's contingency assumptions are that a lack of business readiness will lead to queues of thousands of lorries, with Kent - which is home to the Port of Dover, operating an access permit for hauliers.
A presentation, seen by the BBC, only identified room to fast track between 70 and 100 lorries of perishable goods per day should there be tailbacks, he said.
The authorities have chosen to focus on "fish and chicks" - live and fresh seafood, often transported from Scotland to French restaurants, as well as day old chicks. No other commodities have been added to the list, he adds, raising fears among other food exporters.
There's no denying that the prospect of the pain of no deal at all with the UK certainly weighs on EU minds.
But Europe's leaders are keen to clarify they won't personally intervene in the current impasse in trade talks.
Behind the scenes, leaders are involved in discussions with their negotiators, but they don't want to be face-to-face, or ear-to-ear, with Boris Johnson in public.
Concessions will have an impact on the whole single market - and therefore all member states, as a collective.
Mr Johnson said on Friday a no-deal Brexit was now "very, very likely".
Mrs von der Leyen told reporters that the two sides were still "apart on fundamental issues".
The EU has set out contingency measures to ensure UK and EU air and road connections still run after 31 December.
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