KYIV, Ukraine -- A few hundred people marched to the Russian Embassy in Kyiv on Tuesday to demand that Russia free Ukrainian pilot Nadezhda Savchenko, whose cause also was taken up by the U.S. vice-president and supporters elsewhere.

Even in Moscow, a few dozen people rallied in support of Savchenko, but police broke up the demonstration and detained about 30 protesters, the Interfax news agency reported.

Savchenko was captured in June 2014 while fighting with a Ukrainian volunteer battalion against Russia-backed rebels in eastern Ukraine. She is now on trial in southern Russia, accused of acting as a spotter who called in co-ordinates for a mortar attack that killed two Russian journalists and several other civilians.

The Ukrainian government says she was abducted and should be treated as a prisoner of war.

Savchenko has been on a hunger strike since Thursday, when the judge adjourned her trial without allowing her to give her final statement. The trial is expected to resume Wednesday, with a verdict possible this week.

"During the past 20 months, she has become a symbol of Ukrainian national pride and strength," U.S. Vice-President Joe Biden said in a statement.

Biden said Savchenko has been "unjustly imprisoned" and the U.S. is calling on Russia "to make the right choice -- to drop all charges and release her at once."

Czech Deputy Prime Minister Pavel Belobradek said human rights and international law are violated in Savchenko's case and that he would approach Russian President Vladimir Putin with a letter about it.

The demonstrators who marched to the Russian Embassy carried small signs that read "Free Savchenko" and were decorated with flowers in honour of Women's Day, a public holiday in Ukraine and Russia.

Among those taking part were members of Ukraine's parliament and Maria Varfolomeeva, a journalist who was released last week after spending more than a year held by rebels in eastern Ukraine.

The demonstration was calm, in contrast to a protest outside the embassy on Sunday when some of the participants had pelted the building with eggs and thrown rocks through a window.

Karel Janicek in Prague contributed to this report