It was just after 8pm and darkness was falling one day last week when my friend Pawel Reszka, a Polish correspondent with his country's Rzeczpospolita newspaper, stepped out of his Moscow office to get some cigarettes.

There was just enough time to nip to the shop before making a final call and meeting deadline on his story: an investigation into two recent attacks on Polish diplomats in the Russian capital.

Exactly 18 minutes earlier, Pawel - a big, gregarious man with a zest for life - had appeared on television in a pre-recorded interview saying how safe he felt in Russia.

As he headed home through the underpass beneath Kutuzovskiy Prospekt, a young man sprinted ahead and blocked his path. Turning round he saw four others closing in on him. Then he felt a blow to the back of his head.

The thugs pushed him to the ground and continued kicking and punching for several minutes without a word before running off.

"I look like a bad boxer who went 15 rounds with Mike Tyson," Pawel admitted, when I finally got through to him after he was released from hospital. His face was covered in purple bruises, he limped and his back was agony. The thugs had taken nothing.

Though the culprits are still at large, the motive for the attack on Pawel and the two diplomats seemed clear - it was revenge for the mugging of three Russian diplomats' children in Warsaw.

That initial attack on the children prompted the Kremlin to speak of an "unfriendly act" and demand an apology from Poland. Pawel believes that President Vladimir Putin's intemperate reaction fuelled public resentment, which in turn led to the attack on him in the subway.

"In Russia, when the president leads, the people tend to follow," he said.

In a wider sense, the tit-for-tat beatings are just the extension of a growing political tussle between these old enemies, who have a history of conflict and bloodshed.

As with all healthy vendettas, each side is wont to drag up and polish off old grievances. Poland is still unsatisfied with the apology given by Mikhail Gorbachev over the 1940 Katyn Forest massacre in which the Soviets executed 21,000 Polish army officers and intellectuals. Russia dismisses many Polish complaints as exaggerated and outdated.

Every now and then the simmering conflict comes to a rolling boil. Poles vented their frustration over being left out of speeches during Victory Day celebrations in Moscow in May by boycotting a visiting tour of the Bolshoi Theatre.

But from the Kremlin's viewpoint what really stuck in the craw was the Polish president Alexander Kwasniewski's support last year for the "orange revolution" in Ukraine.

Kwasniewski mediated in the crisis that brought Viktor Yushchenko to the presidency after weeks of street protests in Kiev, and he later commented that "for every superpower, Russia without Ukraine is a better solution than Russia with Ukraine".

That infuriated Putin, who was forced to swallow his failure to influence the election outcome in his strategic backyard as a bitter personal defeat.

Now Poland, as a member of the European Union, is seeking a new role as intermediary between the two halves of the continent.

"Poland wants its eastern neighbourhood like Ukraine and Belarus to become democratic and western-orientated," said Adam Eberhardt of the Polish Institute of International Affairs. "But Russia realises that if that happens it will lose its influence in the region."

Roman Manyakin, a political analyst in Moscow, counters that Ukraine's Warsaw-backed orange revolution has turned out to be a failure. "What we've seen there - and Kwasniewski contributed to it - is simply a change of power from one clan to another. It's provoking a lot of instability."

Fortunately, in spite of the gnawing tensions, relations between ordinary Poles and Russians are often warm. They are, after all, brother Slavs.

Pawel, who reads Pushkin, has a Russian girlfriend and can neck vodka like a bureaucrat, is not going anywhere. "I love it here and I'm going to stay," he says with a grin from behind his mask of bruises.