Polish President Aleksander Kwasniewski has said an attack on him by Russian President Vladimir Putin was "unfair".
Mr Kwasniewski: Mr Putin said he was looking for a job
Mr Putin suggested on Thursday that Poland was working with the West to isolate Russia, after the election crisis in Ukraine.
Mr Kwasniewski mediated in the crisis, helping to organise roundtable talks.
"The words said today by Putin, in my opinion, are unfair words, a price that Poland and I must pay for our involvement in... Ukraine," he said.
Mr Putin was asked at a Moscow news conference to respond to a comment by Mr Kwasniewski in the Polish weekly, Polityka, that "for every superpower, Russia without Ukraine is a better solution than Russia with Ukraine".
He replied: "If we interpret this as striving to limit Russia's ability to develop relations with its neighbours, then it means a desire to isolate the Russian Federation."
The Russian president also said he would ask US President George Bush whether this was US policy when they met in Slovakia in February.
He insisted that Russia had no intention of annexing any country.
Mr Kwasniewski said Mr Putin had misinterpreted his words.
"We are happy that a democratic Russia and a democratic Ukraine are such active members of the modern world, and I believe it will stay like this," he added, underlining his great respect for Mr Putin.
Mr Putin openly backed Ukrainian Prime Minister Viktor Yanukovych to win the country's presidential election.
Mr Yanukovych was initially declared the winner, but the second round of voting was annulled due to massive fraud after massive demonstrations by supporters of opposition leader Viktor Yushchenko.
Mr Yushchenko is now favoured to win the re-run on Sunday.
President Putin added a personal note to his criticism of Mr Kwasniewski, adding that the Polish leader seemed to be "looking for a job because his mandate is about to expire".
Mr Kwasniewski, for his part, said: "I expected my engagement in Ukraine to bring a reaction, and it did".
He added that it was the price he had to pay for resolving a political crisis and developing democracy in Poland's eastern neighbour.
Mr Putin criticised the "revolutions" that have taken place in Georgia and Ukraine - dubbed the "rose revolution" and the "orange revolution" respectively - saying that "they will think of something like blue" next time.
Rose and blue are colours associated in Russia with homosexuality.
"If you have permanent revolutions you risk plunging the post-Soviet space into endless conflict," he said.
He said he hoped isolating Russia was not the goal of US policy.
"If it's indeed so, then the position on Chechnya is becoming more understandable. That means that there, as well, a policy aimed at creating elements that would destabilise the Russian Federation is being conducted," he added.