Prof Nutt said ministers ignored his advice in reclassifying cannabis
MPs have asked Home Secretary Alan Johnson to explain his decision to sack the government's chief drugs adviser.
The Commons Science Committee has written to him asking for clarification of the reasons for the decision and the sequence of events leading up to it.
It wants to know whom he consulted before removing Professor David Nutt and whether the adviser broke any rules in making comments about cannabis risk.
Mr Johnson said Prof Nutt overstepped the mark in criticising drug policy.
Version of events
The home secretary said he lost confidence in the chairman of the advisory panel on the misuse of drugs after he suggested cannabis posed less of a risk than alcohol and tobacco.
Prof Nutt's sacking led to an outcry in the scientific community and prompted two other members of the panel to quit.
The committee has discussed holding an inquiry into the affair but wants to gather evidence from the main players before deciding whether to conduct hearings.
Lib Dem MP Phil Willis, the committee's chairman, said he was asking the home secretary for his account of events leading up to the sacking in light of the "considerable" media coverage of the story.
He said the committee was keen to ascertain whether Prof Nutt had breached the panel's remit or the code of conduct for scientific advisers in any of his public comments about the relative risk of different drugs.
In addition, Mr Johnson has been asked to confirm whether he consulted Professor John Beddington, the government's chief scientific adviser, before taking the decision and if not, to explain why.
The home secretary is also being pressed on his views on the future of the advisory panel and whether, following the spate of resignations, it has "sufficient expertise" to carry out its functions.
The committee has also written to Prof Nutt and Prof Beddington asking them for their version of events.
In July, the committee recommended that members of advisory committees should not be criticised for publishing scientific papers or making statements as professionals independent of their public role.
It also urged ministers to speak up in support of scientific advisers whenever their independence was threatened by political actions.
Prof Nutt has criticised the decision to sack him and floated the idea of setting up a separate advisory body.
Gordon Brown has backed the home secretary's decision, saying the government could not afford to send "mixed messages" on drugs.