Poland takes its turn at EU helm
Poland has taken over the rotating presidency of the EU for the first time since it joined the bloc in 2004.
Its priorities for the six-month term include building relations with the EU's eastern and southern neighbours, and strengthening the EU single market.
Poland, enjoying an economic growth rate of about 3.5%, also says it wants to promote further EU enlargement.
Croatia has completed its accession negotiations and is on track to become the EU's 28th member state in mid-2013.
The rotating presidency is less powerful than in the past, now that the EU has a full-time President of the European Council - Herman Van Rompuy - and a foreign policy chief, Baroness Ashton.
Polish Prime Minister Donald Tusk hopes that the EU presidency will boost his Civic Platform party and help it retain power in national elections in October.
At a handover ceremony in Warsaw, Hungary's Prime Minister Viktor Orban presented Mr Tusk with a cask of wine, receiving a sabre as a gift in return.
Poland is marking its new EU role with special concerts and fireworks on Friday.
The BBC's Adam Easton in Warsaw says Poland wants to portray itself as a regional power with ideas worth heeding, with perhaps chief among them a focus on the bloc's eastern neighbours.
It hopes an "Eastern Partnership" summit in September, gathering leaders from the EU and six former Soviet nations, will give the initiative new impetus, and wants to conclude negotiations on a free trade agreement with Ukraine.
Another priority will be trying to help the EU in its efforts to manage the sovereign debt crisis threatening Greece and the eurozone.
Poland has not adopted the euro, but has strong trade links with eurozone countries.
The eurozone has put in place a new budget surveillance mechanism to help contain the Greek debt crisis and prevent anything similar in future.
The outgoing head of the European Central Bank (ECB), Jean-Claude Trichet, told Euro MPs on Thursday that "crisis prevention is absolutely of the essence".
EU member states need to keep a close watch on each other's unit labour costs, competitiveness and budget imbalances, he said.
Differences about how best to tackle Europe's economic challenges are expected to emerge during the start of negotiations over the EU's next long-term budget.
Poland argues that a bigger budget will encourage growth throughout the bloc.
Countries that have introduced austerity programmes or are net contributors to EU finances, such as Germany and the UK, want a smaller budget.
Environmentalists have expressed concern that Poland, which relies heavily on coal for energy supplies, will be reluctant to support a green agenda.
Poland, with a population of 38 million, is the largest country to join the EU since its expansion in 2004.
It is the fourth former communist state to hold the EU presidency, after Slovenia in 2008, the Czech Republic in 2009, and Hungary in the first half of 2011.
Recent surveys suggest that backing for EU membership within Poland stands at more than 80%.