Senior officials had last week discussed whether UK nationals should be treated as “third country” nationals as part of its no-deal planning, which would require travellers to buy a 60 euro permit to cross the channel.
But EC vice president Frans Timmermans said the council of commissioners had agreed to change the rules - as long as the UK did the same for EU citizens after next March.
He told a Tuesday press conference in Strasbourg: “On visas we propose to amend the visa regulation to allow UK nationals to be exempt from any visa requirement for short stays in the EU once EU law stops applying to the UK.
“But of course an important point: this is entirely conditional on the UK also doing the same thing for EU nationals, reciprocating.”
Number 10 welcomed the proposals from the European Commission.
A Downing Street spokeswoman said: “We have said that we want to ensure reciprocal visa-free travel for tourists and short-term visitors with the EU.”
A document released by the Commission says the rules would apply to Britons travelling to Schengen Area nations, which includes all western European EU member states and eastern ones including Poland, Latvia, Lithuania, Estonia, the Czech Republic and Slovakia.
Travel to Iceland,
Liechte-nstein, Norway and Switzerland, which are “Schengen-associated states”, would also be covered, it said, as well as Romania, Bulgaria, Croatia and Cyprus, which are EU members but are not yet part of the free-travel area.
It would apply to trips of up to 90 days within any 180-day period, starting from
30 March in the event of a no-deal Brexit and from the end of any transition period if a deal is achieved.
Adding to Mr Timmerman’s remarks, it also says: “This proposal is entirely conditional upon the UK also granting reciprocal and non-discriminatory visa-free travel for all EU Member States, in line with the principle of visa reciprocity.
“The UK government has declared its intention not to require a visa from citizens of the EU27 Member States for shorts stays for the purposes of tourism and business.
“EU rules on non-EU nationals travelling to the EU, such as those on border control, would of course apply to UK citizens once they are no longer EU citizens.”
The Commission urged the European Parliament and Council to back the change quickly “so that it can be adopted in good time before 30 March 2019”.
Brexit will also see UK nationals barred from the fast lane at airports and other national boundaries.
An EC document on travel arrangements says Britons “will not be entitled to use the separate lanes” for citizens of the EU, European Economic Area (EEA) and Switzerland “and will be subject to thorough checks of all entry conditions for third country nationals upon entry”.
Those staying in EU nations for more than 90 days will require a residency permit or a long-stay visa issued by the country they are staying in.
Lib Dem Brexit spokesman Tom Brake said: “Now we are beginning to realise why the Brexiters wanted everyone to get new, blue passports; to collect all the visa stamps they will need to travel as freely as they do now.
“This will come as a real shock to those who spend their winter months in Spain or Portugal and will now see additional costs and potential queues providing extra baggage.
“Theresa May and Jeremy Corbyn need to start listening to the people up and down the country, the majority now want a People’s Vote, and the chance to walk away from this terrible Tory mess.”