South Korea's parliament on Monday ratified a trade deal between Seoul and London that will take effect automatically following Britain's departure from the European Union.

The free trade agreement essentially replicates the terms of the existing EU-South Korea deal and comes in the face of continuing uncertainty over a Brexit timetable.

The new FTA secured "stability and continuity" in South Korea's trade environment with Britain amid "increasingly complex situation over Brexit", Seoul's trade ministry said in a statement.

"The two countries have completed domestic procedures and the Korea-Britain FTA will take effect automatically when Britain leaves the EU in the future," it said.

The ministry added the new FTA maintains the "same levels" of benefits as the agreement with the EU, and will take effect immediately in the event of a no-deal Brexit.

If a deal is reached between Britain and the EU, the FTA will be implemented after the transition period, it added.

Britain is South Korea's second-largest trade partner in the European Union, but accounts for less than two percent of the country's overall trade. (AFP)