BRUSSELS, Oct 13 (Reuters) - The European Union has "serious concerns" about the United Kingdom's implementation of the agreement on its withdrawal from the bloc but believes a deal on future relations is still possible, a senior European Commission member said on Tuesday.

"As you know, the EU has serious concerns about the level of implementation on the UK side," Maros Sefcovic told a news conference after a meeting of European affairs ministers that was briefed by the bloc's Brexit negotiator, Michel Barnier.

He said there would be a further EU-UK meeting next week on implementing their divorce treaty.

Clinching a new trade deal that would need to be in place by the end of the UK's status quo transition period on Dec.31 was "very difficult but still possible", he added. (Writing by John Chamlers)