Germany's "Der Spiegel" says Chancellor Angela Merkel could cancel her visit to Ukraine during the Euro 2012 football tournament in June if jailed former Prime Minister Yulia Tymoshenko is not yet released.
Tymoshenko, 51, is serving a seven-year prison term for abuse of power in the city of Kharkiv and has been on a hunger strike for more than a week.
She is also facing fresh charges that she and her supporters, as well as international rights watchdogs, say are similarly political in origins.
"Der Spiegel" magazine reported that if Merkel did not go to Ukraine, other members of the German cabinet might follow suit.
The magazine did not name any sources for the report.
The case has strained ties between Ukraine and the European Union, which says Tymoshenko's jailing in October was politically motivated.
She has reportedly been on hunger strike for more than a week.
Her daughter, Yevhenia, emerged from a recent visit expressing fresh concerns
for Tymoshenko's health, with images that appear to show bruises from rough treatment at the hands of her jailers.
Based on Reuters and RFE/RL reporting