SOFIA (Reuters) - Bulgaria has threatened to block North Macedonia’s path towards European Union membership and said it should recognise that both its national identity and language have Bulgarian roots, its foreign minister said on Friday. Ekaretina Zaharieva said Bulgaria, which focused its first period as the EU’s rotating presidency in 2018 on the swift accession of western Balkan nations to the 27-member bloc, could veto the formal launch of accession talks with North Macedonia next month unless the two sides can resolve the issue. This poses yet another challenge for Skopje, which agreed to add “North” to its name to resolve a decades-old standoff with Greece and clear its path to entry into both the EU and NATO. The renamed North Macedonia joined NATO earlier this year. Bulgaria is losing patience over what it sees as North Macedonia’s reluctance to implement a friendship treaty the two countries signed in 2017.