The Congress claimed on Wednesday that Himachal Pradesh BJP president Rajeev Bindal's resignation showed that the corruption allegations in the Health Department were true.
In a joint statement, state Congress president Kuldeep Singh Rathore and legislature party leader Mukesh Agnihotri said the Bharatiya Janata Party cannot get "rid of the sin of corruption" in the Health Department amid the novel coronavirus pandemic.
The comments come hours after Mr Bindal resigned from his post within four-and-a-half months of his appointment.
Health Services Director Ajay Kumar Gupta was arrested on May 20 by the State Vigilance and Anti Corruption Bureau after a 43-second audio recording went viral, in which he purportedly asks the other person for a bribe of Rs 5 lakh.
The Congress said Chief Minister Jairam Thakur cannot evade moral responsibility in the entire matter as he was also holding additional charge of Health Department.
The party demanded that the probe into the scam should be entrusted to a sitting high court judge as it had no faith in the probe being conducted by the vigilance bureau.
The Congress leaders said that Mr Bindal's resignation established the allegations levelled against the state government.
They said the entire matter should be probed in a free-and-fair manner and no attempt should be made to cover up the matter.
Meanwhile, Congress secretary Sudhir Sharma said Mr Bindal's resignation "shows the level of involvement in the scandal in the Health Department".
This shows that all the purchases made so far in the Health Department due to the coronavirus pandemic are "under suspicion", he added.