Foreign Minister Kang Kyung-wha said Friday that "we are already having serious discussions about this."
She said South Korea's president held talks with British Prime Minister Theresa May about future trade ties on the sidelines of a summit of European and Asian leaders in Brussels.
EU foreign policy chief Federica Mogherini warned that Britain cannot negotiate or conclude trade agreements while it remains a EU member. That includes during any transition period.
May and her European counterparts have said they are open to a transition period after Britain leaves the EU on March 29 that could last anywhere from 21 months to about three years.
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