LONDON, Dec 10 (Reuters) - Britain’s Brexit minister David Frost said on Friday that further "limited progress" on the issue of medicines had been made in talks with the European Union on post-Brexit trade arrangements for Northern Ireland, but there was no agreement. The two sides have been in intensive talks to resolve difficulties over trade between Great Britain and Northern Ireland, a British province that shares a land border with EU member the Republic of Ireland. London has repeatedly threatened to invoke Article 16, an emergency brake in the Northern Ireland chapter of the Brexit deal, a move that could trigger a full-blown trade war between the EU and Britain. "I underlined the need for movement on all the difficult issues created by the (Northern Ireland) Protocol, including customs, agrifood rules, subsidy policy, VAT/excise, & governance including the Court of Justice," Frost said on Twitter after a virtual meeting with European Commission Vice-President Maros Sefcovic. "We will not find a durable solution that does not deal with all these problems," he said. Talks will continue this coming week. “Maros Sefcovic and I will talk twice to steer the process, in the hope of making worthwhile progress towards agreed solutions before Christmas,” Frost added. Sefcovic said on Twitter it was "crunch time for medicines", with the EU Commission ready to amend EU legislation. He added he would talk to Frost on Dec. 15 and 17.