People Before Profit's Bríd Smith says the state's actions in dealing with covid-19 outbreaks in the direct provision system is "an abuse of human rights".
More than 160 residents of direct provision across the country are known to have tested positive, while around 75 people living at one centre in Co Kerry are being treated as close contacts.
The Movement of Asylum Seekers says residents there are being blamed for failing to socially isolate, but find it impossible to do so.
People Before Profit TD Bríd Smith says the message being given to asylum seekers is "insulting".
"The letter says that the residents have been putting themselves in danger because they haven't been self-isolating," she said.
"We have some People Before Profit in that particular town who have been, along with other local people, delivering food and baby stuff to them.
"They've got to know the residents a bit and they say it is appalling because most of these residents have to live three or four to a room."