LONDON, Dec 21 (Reuters) - Britain"s foreign minister Liz Truss, thrust into post-Brexit talks with Brussels after the resignation of Brexit minister David Frost, said London"s position remained unchanged and the process needed to speed up in the New Year. "Our preference remains to reach an agreed solution," Truss said after a first online meeting with her European Union counterpart Maros Sefcovic on Tuesday. "If this does not happen we remain prepared to trigger Article 16," she said, referring to a safeguard measure in the Northern Ireland protocol of the Britain-EU divorce deal. Following the meeting, Sefcovic said on Twitter: "I"m committed to continue working towards a conclusive understanding with the UK on practical solutions for NI stakeholders. The EU"s position is known. Our goal: stability and predictability." Frost quit on Saturday, citing differences with Prime Minister Boris Johnson over the direction of his government. His departure triggered speculation that London might soon take a different stance in its attempt to renegotiate key parts of its post-Brexit trade deal with the EU. Truss said Britain still wanted to end the role of the European Court of Justice as the final arbiter of disputes, a flashpoint for both sides.