British international trade secretary Liam Fox and Swiss Economy Minister Guy Parmelin signed the bilateral trade agreement in Bern on Monday.
"This new agreement lays the foundations for the two parties to continue their sound economic and trade relations once the United Kingdom has left the EU," the Swiss government said in a statement (here in English).
The UK has signed a trade continuity agreement with Switzerland, ensuring 🇬🇧 and 🇨🇭 businesses can continue to trade freely when we leave the EU.#Didyouknow UK-Swiss trade totalled over £30bn in 2018. #FreeTradeUK pic.twitter.com/VvMJZ8ZLLN— Department for International Trade (@tradegovuk) February 11, 2019
Switzerland is not a member of the EU, but its relations with Britain are based on a long line of bilateral agreements between Bern and the bloc.
If London and Brussels manage to reach a deal for an orderly Brexit, the bilateral agreements between Switzerland and the EU will continue to apply to Britain until the end of the transition period, the statement said.
But in the case of a "no-deal" Brexit, those agreements will no longer apply to Swiss-British relations, and the new bilateral trade agreement between the two countries will kick in.
"Should the United Kingdom leave the EU on 29 March without a deal, the agreement will come into effect on a provisional basis from 30 March 2019," the government statement said.
Britain is currently one of Switzerland's biggest trading partners.
In 2017, Switzerland registered 11.4 billion Swiss francs ($11.4 billion, €10.1 billion) in exports to Britain, making it the Alpine nation's sixth largest export market.
Switzerland meanwhile is Britain's fifth biggest export partner outside the EU.
L’avenir de nos relations commerciales avec le Royaume-Uni est assuré. Le conseiller fédéral Guy Parmelin signe avec le ministre britannique du commerce international @LiamFox l’accord qui règle l’après #Brexit entre les deux pays. https://t.co/kKe7lB95HB pic.twitter.com/jTu3Ntjcog— WBF DEFR EAER (@DefrWbf) February 11, 2019
The Swiss government is pursuing a strategy dubbed "Mind the Gap", which is intended to stabilise British ties after Brexit.
It said it had reached a range of agreements with London aimed at ensuring "that the existing mutual rights and obligations in its relationship with the UK will continue to apply as far as possible after the UK leaves the EU, and to expand them in certain areas."
Switzerland and Britain have already signed agreements shoring up their cooperation in the areas of road transport, air transport and insurance.
They have also signed a deal to preserve the rights of some 43,000 British nationals living in Switzerland and the 35,000 Swiss residing in Britain after Brexit.