The Prime Minister was today advised to refrain from insulting European political parties.
Tory Daniel Kawczynski (Shrewsbury and Atcham) said Gordon Brown's comments on Poland's Law and Justice Party were a "great insult" to the Polish president.
But Mr Brown said the Tories should look again at the policies of the parties with which they were forming an alliance in the European Parliament.
During Prime Minister's questions, Mr Kawczynski, who is of Polish descent, said: "The Prime Minister's insult to the Law and Justice Party of Poland yesterday in his European statement is a great insult to the President of Poland (Lech Kaczynski) who is a member of that party and to the Polish people who elected that party into office.
"No matter what he may think of the Law and Justice Party, he must understand that as Prime Minister of the UK he has a duty to implement basic diplomatic procedures."
Mr Brown yesterday described the party as "extreme right-wing" during a Commons statement on the European Council.
He told Mr Kawczynski: "I have very good relationships with the president you're talking about.
"As far as the Polish Law and Justice Party, I think the Conservatives should look at the policies of the parties they are having dealings with."
Labour's Phil Wilson (Sedgefield) asked the Prime Minister whether it should be the role of mainstream UK political parties to associate with such parties.
Mr Brown replied: "Isn't it remarkable that the Conservatives have formed an alliance in Europe that excludes the German Christian Democrats, excludes the French party of President Sarkozy, excludes the Italian party of Prime Minister Berlusconi ... "
He was interrupted by loud jeers from the Tory benches but continued: "They are now isolated on the fringes of Europe."