In December, Danes solidly rejected the referendum to replace the current opt-out on EU justice and home affairs with an opt-in model that would keep Denmark a full member of Europol – the EU's law enforcement agency that tackles organized crime, trafficking and terrorism.
King, who is being described as the UK's ‘final European Commissioner', faced three hours of questioning from MEPs in Strasbourg on Monday that focused largely on his loyalty to the EU in light of Brexit.
But during the questioning, King also fielded a question from Danish MEP Anders Vistisen on Denmark's ability to remain in Europol.
“I support member states' engagement with Europol. But it needs to happen within the framework of Treaty,” King said, according to Danish news agency Ritzau.
“Denmark has Protocol 22 [the Justice and Home Affairs opt-out, ed.] and that limits cooperation in this area. There was a referendum on it and we need to accept the result of the referendum,” he continued.
Since the December referendum, the Danish government has been working on finding a solution to remain part of Europol through some sort of parallel agreement.
But Danish PM Lars Løkke Rasmussen quickly found on his first post-referendum trip to Brussels that European leaders aren't particularly interested in making special arrangements for Denmark.
“Full Danish participation cannot happen. I can sense no reluctance whatsoever, but there was a Danish referendum in which the Danes opted not to make use of an opt-in. Therefore, it will be a membership of another character,” Rasmussen said in December.
European Council President Donald Tusk also warned during a May visit to Copenhagen that a parallel agreement to keep Denmark in Europol is "maybe impossible".
King's comments on Monday seemed to indicate that Denmark is likely to be on the outside looking in when Europol becomes a supranational body on May 1, 2017.
The comment by King irked the eurosceptic Danish People's Party, which wants to remain a part of Europol despite opposing the referendum to replace Denmark's opt-out with an opt-in model.
“It is a most peculiar announcement from the British Commissioner. The UK need all the friends it can find in the EU to ensure a proper agreement. Denmark is one of the few countries that we help the UK,” party spokesman Kenneth Kristensen Berth told Ritzau.
King is expected to be approved as security commissioner on Thursday.