Two asylum seekers have sewn their lips together and started a hunger strike in Greenock Prison.
Dungavel, from where the two men were transferred to prison
The men, a Russian and a Palestinian, were transferred to the jail from the Dungavel detention centre.
The Scottish Prison Service (SPS) would not comment on individual cases. Robina Qureshi, of Positive Action in Housing, criticised the Home Office.
She said the men were being treated like criminals and should not have been transferred to the jail.
Asylum seekers are usually held at Dungavel detention centre in Strathaven, Lanarkshire, while their claims are evaluated.
Ms Qureshi told BBC Radio Scotland that the Russian man was taken to Dungavel in January 2003 and transferred to Greenock jail two weeks ago.
She said: "Since then he has gone on hunger strike and sewn his lips up, as has another Palestinian asylum seeker, whose name we don't know.
"This is not about people who have been left in Dungavel for a matter of days, they have been left for up to one-and-a-half years to basically rot and that's leading them to such despair that they are considering suicide as their only option.
"The response of the Home Office is to simply dump them in a prison alongside convicted criminals."
She said it was wrong for asylum seekers to be effectively punished by the system while their claims were processed, then put into prison.
A spokeswoman for the SPS said: "There are arrangements in place in exceptional circumstances where the SPS can accept asylum seekers.
"They are accepted only in exceptional circumstances under the agreed protocol between the SPS and the Immigration Service."
The Home Office too declined to comment on individual cases.
But a spokeswoman said: "The Home Secretary's commitment to end the routine use of prison accommodation to hold immigration detainees has been fulfilled and the practice ended in January 2002.
"It was made clear at that time that exceptions would have to be made for reasons of security and control, i.e. because an individual could threaten and disrupt the orderly working of the immigration centre, the staff or other detainees."
Ms Qureshi also raised the case of a Nigerian man she said was recently transferred from Dungavel to prison because he had suicidal tendencies.
"These people are innocent, they are not criminals," Ms Qureshi went on.
"The Home Office clearly sees no difference between Dungavel and Greenock Prison because it is using them as part of the overall detention system."
The Scottish Socialist Party called on the Scottish Executive to make a statement on the use of Greenock Prison to hold asylum seekers.
SSP justice spokesman Colin Fox said Justice Minister Cathy Jamieson should address the Scottish Parliament as "a matter of urgency".
He said: "The use of Scottish jails to hold asylum seekers who have committed no offence and who have not been charged with any crime is an extremely serious development.
"The executive can no longer remain silent when its ministers are now directly involved in the way that asylum seekers are being treated in Scotland."