For the time being, he added, Warsaw will "maintain the results of the negotiations" in order to avoid any risk that the president, whose approval of the EU's new Lisbon Treaty is also needed, would halt the ratification process.

In an effort to improve the country's reputation of being a trouble-maker on European issues, Poland is set to be the first to ratify the EU bloc's new institutional set-up, agreed in October.

The citizens' rights document, legally binding by the treaty, is seen in Poland's conservative circles as a backdoor to allowing abortions, euthanasia or gay marriages.

"If we signed the Charter without the British protocol, [and I am] partisan to such a solution, it could be an obstacle to ratify the treaty in our country", Mr Tusk said.

According to insiders, Poland is considering adopting a one-sided declaration saying the country will sign up to the rights charter with a year.

European Commission president Jose Manuel Barroso reiterated that Brussels prefers not to have opt-outs, but added that he "very much understands the reason why there is the need to keep the opt out for the time being".

"It is up to Polish government how and when to opt in", Mr Barroso said.

In addition, the commission president praised the dramatic change in Poland's diplomatic style since the October elections and referred to new Polish prime minister as a friend.

Both politicians avoided speaking about any topic where there are differences, such as blocked talks on a new EU partnership agreement with Moscow.

Instead, Mr Barroso said: "What is important is the attitude. When there is a difficulty, if we try to find a solution in a constructive way, I know this will be the spirit".

But when speaking about election results in Russia - questioned not only by Russian opposition, but also by the Organization for Security and Cooperation in Europe or Germany - Mr Tusk made it clear he would not soften the Polish stance on certain issues.

"We should not in Europe afford ourselves to be tolerant to a situation when certain democratic standards are not being respected...You cannot turn a blind eye to what happened, there are results of elections and these results are not going to be challenged by anyone in Europe", he said.

At the same time, the Polish leader added that his "government is ready to take a course of action which would speed up efforts in Russia to entrench and solidify democratic standards over there".