The Czech Republic has avoided large-scale migration through its territory as most of the hundreds of thousands of people fleeing poverty and war in the Middle East via the Balkans to Germany take an easier route through neighbouring Austria.
The alleged strike takes place at a newly open facility in Drahonice, roughly 90 kilometres (55 miles) west of the capital Prague.
"In the morning it was 44 people who started the hunger strike, then in the afternoon it was over 60," volunteer Petra Damms told Reuters in a phone interview on Tuesday.
"It is not because of the physical conditions they strike, it is the extending of their detention, they don't know why."
Damms said tensions rose after 40 people were transported out from Drahonice at 3 a.m. on Tuesday, fuelling detainee fears of deportation.
Officials at the detention centre were not immediately available for comment.
Most of the 144 people currently in Drahonice were brought from another detention centre in Bela-Jezova, which has been harshly criticised recently due to the conditions there.
The Czech detentions, usual lasting up to 90 days, apply to the vast majority of migrants who do not claim asylum in the country. A total of 7,201 have been detected in the first nine months of this year. Many continue their journey to Germany upon release.
The Czechs voted in September by a small minority against quotas to distribute asylum seekers across the European Union, putting them on collision course with other EU countries.