Poland's Prime Minister Donald Tusk has criticised the conduct of Russia's election, during his first talks with top EU officials since taking office.
Donald Tusk still wants to improve ties with Moscow
His comments in Brussels contrasted sharply with those of French President Nicolas Sarkozy, who congratulated President Vladimir Putin on Monday.
The EU's Portuguese presidency said Sunday's parliamentary election failed to meet international standards.
A Polish-Russian dispute has fuelled EU-Russia tensions in the past year.
The previous Polish government blocked talks on a new EU-Russia agreement after Russia imposed a ban on imports of Polish meat products.
Referring to the Russian election, Mr Tusk said "we should not in Europe be tolerant of a situation where certain democratic standards are being broken".
EU voices concern
The EU statement on Tuesday echoed that criticism, noting that "there were many reports and allegations of media restrictions as well as harassment of opposition parties and NGOs" during the election.
It called on Russia to investigate the allegations about irregularities.
Mr Tusk received a warm welcome from the European Commission president, Jose Manuel Barroso.
Mr Tusk was critical of the Russian authorities' treatment of the opposition activist and former chess star Garry Kasparov, whom he described as "my political friend".
Mr Kasparov was detained during the election campaign and his party was prevented from taking part in the election.
But Mr Tusk added that he wanted ties between Warsaw and Moscow to improve.
Meanwhile, Mr Sarkozy's call to President Putin has angered human rights groups in France and the opposition Socialist Party.
New EU-Poland chapter
In a significant change from the Eurosceptic stance of his predecessor Jaroslaw Kaczynski, Mr Tusk said there was no conflict between the interests of Poland and those of the European Union.
"Along with others who have fought for the European Union, I will stand up and defend the European interest as well," he said.
Our European Affairs correspondent Oana Lungescu says top EU officials were all smiles, welcoming Donald Tusk as a dedicated European and an old friend.
It was a marked contrast to Mr Kaczynski, who shocked the rest of the EU by demanding more voting rights in exchange for the 6.5 million Poles killed by Germans during World War II.
His government had also decided to opt out of a European charter of fundamental rights because it thought it would encourage gay marriages.
Britain has also decided not to adopt the charter.
Mr Tusk said Poland could reconsider its position on the charter in the future, but only after ratification of the new EU Reform Treaty, of which the charter is part.
Mr Tusk has also been having talks with Nato officials about Russia and the controversial US missile defence system.
Jaroslaw Kaczynski agreed to have a missile interceptor base built in Poland and Mr Tusk's government says it wants to reassure Moscow about the project while working in partnership with its Nato and EU partners.
Russia and Poland will have their highest-level talks for more than a year when the Polish Foreign Minister, Radek Sikorski, meets his opposite number Sergei Lavrov in Brussels on Thursday.