Russia and Slovakia tightened their borders with Ukraine on Tuesday as the World Health Organization began investigating a suspected swine flu outbreak.
The death toll from flu has climbed to 71 since the outbreak struck last week in the western city of Ternopil, Prime Minister Yulia Tymoshenko said. But blood tests have yet to determine how many of these deaths were from the new and aggressive H1N1 strain.
Polish Prime Minister Donald Tusk has called on the European Union to help neighbouring Ukraine fight a swine flu epidemic, saying its further spread is threatening the wider bloc.
Ukraine shut schools, banned public meetings and restricted travel earlier this month in an attempt to combat the H1N1 flu epidemic, which has caused public concern in Poland.
"The character of this threat demands that rapid action be undertaken at the European Union level," Tusk wrote in a letter to European Commission President Jose Manuel Barroso and Swedish Prime Minister Fredrik Reinfeldt, who holds the rotating EU presidency.