Tusk travelled to the Belgian capital after being sworn into office on Wednesday morning, Polish state news agency PAP reported.
During the EU-Western Balkans summit, Poland's new prime minister was set to hold talks with leaders from Albania, Bosnia and Herzegovina, Montenegro, North Macedonia, Kosovo and Serbia, according to officials.
Discussions were expected to focus on the progress made by the Western Balkans countries on gradual integration with the EU, as well as on green policies for the region and combating Russian disinformation, among other topics.
Meanwhile, the European Council meeting starting on Thursday will focus on "continued EU support for Ukraine and its people" amid the Russian invasion, EU enlargement policy, as well as efforts to bolster the bloc's security and defence capability, reporters were told.
Poland stresses the role of the EU's cooperation with NATO, as well as the importance of continued support for Ukraine, and the need to "combat illegal migration," officials in Warsaw said.
Poland also supports EU enlargement, including opening accession talks with Ukraine and Moldova, and granting candidate status to Georgia, the new government added, as cited by the PAP news agency.
In an invitation letter to EU national leaders, issued on Wednesday, European Council President Charles Michel said the summit on December 14 and 15 would focus on "continued and sustainable support for Ukraine," a revision of the bloc's budget, defence and security issues, as well as developments in the Middle East, the PAP news agency reported.
Wednesday is day 658 of Russia's war on Ukraine.
Russia invaded Ukraine on February 24, 2022, launching the largest military campaign in Europe since World War II.
(pm/gs)
Source: PAP, European Council