In the early hours of Saturday, 12 people were killed and many injured in an accident of a Polish bus north of the Croatian capital, Zagreb.
The bus slipped off the road on the A 4 motorway and landed in a ditch.
The Polish foreign ministry spokeswoman said all the casualties were Polish citizens.
Polish prime minister Mateusz Morawiecki confirmed on Tuesday that 11 dead and 34 injured as well as 11 dead. He said he had sent health and deputy foreign ministers, Adam Niedzielski and Marcin Przydacz, to the site of the accident.
According to Morawiecki, the bus carried pilgrims to the Catholic pilgrimage site Medjugorje in southwestern Bosnia and Herzegovina.
The Polish health ministry spokesman Lukasz Jasina confirmed that the 12th person had died in the hospital.
We have more fatalities -- the twelfth person. Jasina told the Polish TV channel TVN 24 that the victim died in hospital.
The Croatian newspaper Vecernij List reported on its website that five injured tourists were in a serious condition.
According to the Croatian fire service, the injured people were transported to hospitals in Varazdin and Zagreb.
Croatian public television HRT said that the driver was most likely to have fallen asleep.