One year after the plane crash which killed Poland’s president and 95 others, there is anger over the replacement of a memorial plaque.
A new one with a different inscription making no mention of the 1940 Katyn massacre – the anniversary of which was the reason for the doomed trip – has infuriated grieving Polish relatives.
It is the latest in a series of irritations which have soured Polish-Russian relations.
After Sunday’s ceremony in Warsaw, Poland’s current president, Bronislaw Komorowski, will meet up with his Russian counterpart, Dmitry Medvedev in Moscow on Monday.
Together they will go on to visit the Smolensk crash site and the Katyn memorial when Komorowski is expected to raise the issue of the plaque.
Relations have also been strained after many Poles were dissatisfied with a Russian report into the accident which cleared Russian air controllers of any wrong doing.