The Ministry of Justice has a "disturbing" lack of awareness of devolution, MPs have said.
A report from the Commons Welsh affairs committee criticised the way in which the closure of the Legal Services Commission's Cardiff office was handled.
The LSC had announced restructuring plans in November 2008, with functions at its Cardiff office being transferred to processing centres in England.
But the MPs said they were "shocked" that the LSC's consultation with the Wales Office or the Welsh Assembly Government was "extremely limited".
"This is unacceptable and betrays a poor understanding of the devolution settlement on the part of the Commission," said the committee.
"It appears that Whitehall guidance has been misunderstood on a number of occasions."
The report added: "The Legal Services Commission failed to include the Wales Office in any form of consultation regarding the proposed changes to its Cardiff office. This is unacceptable.
"It runs counter to explicit guidance given to government officials and betrays a poor understanding of the devolution settlement on the part of the Commission.
"It is essential for the secretary of state for Wales to be fully in the picture at the outset and at every stage in the process.
"This is not the first time that the Ministry of Justice (or in this case one of its agencies) has demonstrated a surprising lack of awareness about the devolution settlement and the protocols which are in place in relation to legislation, and, as the department has overarching constitutional responsibilities, we find this disturbing."
Committee chairman Dr Hywel Francis said: "I am pleased that the minister has acknowledged that mistakes were made during this process and that he is seeking more time for this to be done properly.
"It is essential that more time is now allowed for thorough consultation to take place before any decision on the future of the Cardiff office is made."
Dods Parliamentary Communications Ltd