SKOPJE, Jan 18 (Reuters) - The new premiers of Bulgaria and North Macedonia agreed on Tuesday to try to overcome problems that prompted Sofia to block the start of accession talks between the European Union and Skopje. Dimitar Kovacevski, who was sworn in as North Macedonia"s prime minister on Monday, said he and Bulgarian Prime Minister Kiril Petkov had agreed at talks in Skopje to try to improve relations between their countries. Petkov, who took office last month, said he was "a big optimist" about the chances of them achieving results. Bulgaria refused in 2020 to approve the EU’s membership negotiation framework for North Macedonia because of disputes over history and language, but faces pressure from its Western allies in the EU to be more flexible. read more "I start my first working day as the prime minister with one of the most important issues for North Macedonia, and that is learning about conditions for our speedy progress towards European integration," Kovacevski said after Tuesday"s talks. "With colleague Petkov, we agreed to use this new energy and ... improve the relations between the two countries." Bulgaria"s consultative national security council, which includes all leading political parties and other senior officials, has agreed the government should seek a breakthrough but not at the expense of national interests or the rights of Bulgarians in North Macedonia. Petkov said new neighbourly relations would be measured on "real, achieved results" based on what is achieved weekly by working groups covering the economy, infrastructure, culture, EU integration and history. "Today I am a big optimist for our joint action and I believe that the results you will all see will be coming every week, and I hope that what each of the countries hopes to happen in the end, we will have as a result very soon," he said. Supporters of EU membership for North Macedonia say accession would help boost living standards and offset growing Russian and Chinese influence in the Western Balkans. The EU is by far the biggest foreign investor and trade partner of the six countries that emerged from the break-up of Yugoslavia and the ethnic wars of the 1990s.