Parents and pupils protesing outside Lansdowne Primary School last year
The equality watchdog is being asked to intervene in a dispute over possible changes to schools in a Cardiff suburb.
A proposal to close one school with a balance of white and ethnic minority pupils was described as "polarisation" by First Minister Rhodri Morgan.
Now Liberal Democrat Assembly Member Jenny Randerson has officially complained that Mr Morgan may have broken the ministerial code.
She says his comments could pre-empt decisions to be made by a colleague.
One councillor has apologised after calling the option to close Lansdowne Primary School, Canton, "ethnic cleansing".
Mr Morgan, who is the local AM, said in the assembly chamber that phrase was wrong, but polarisation might be accurate.
The proposed reorganisation of Cardiff schools is to meet demand for Welsh-language education in primary schools.
Options include closing or relocating Lansdowne primary school and moving a Welsh medium school, Ysgol Treganna on to the site.
Now the issues have been referred to the Commission for Equality and Human Rights.
Labour councillor Ramesh Patel had described the proposal as "ethnic cleansing", although he has since apologised.
Plaid Cymru's Mohammad Asghar questioned the first minister about the controversy in the Senedd chamber, and asked him to condemn the phrase ethnic cleansing.
Rhodri Morgan, the Assembly Member for Cardiff West, which includes both schools, said in the chamber: "I know the Labour councillor concerned extremely well, and I think he has apologised for the use of the expression ethnic cleansing.
"It was one of those unfortunate phrases, slips of the tongue... he said that he meant to say polarisation.
"A school that has a balance of 53% white to 47% ethnic minority pupils is proposed to be closed by Cardiff county council, and that would undoubtedly lead to an undesirable degree of ethnic polarisation.
"I think that polarisation may be accurate [but] 'ethnic cleansing' is a completely unacceptable phrase."
Cardiff council's plans could have to be approved by the education minister and the Liberal Democrats say Rhodri Morgan's comments effectively prevented a member of his cabinet from making a decision in an open and fair manner.
"The first minister may well have broken the ministerial code so I have asked for an investigation," said Jenny Randerson, AM.
Meanwhile, Plaid Cymru's leader on Cardiff council has referred the comments to the Commission for Equality and Human Rights.
Councillor Neil McEvoy said: "I am shocked by his comments... how he can try to explain away a repugnant phrase like ethnic cleansing is beyond me".
Mr Morgan has issued a statement about any proposal to close Lansdowne, and he too is writing to the Equality and Human Rights Commission.
"If that school were to be closed and the school pupils dispersed to other nearby primary schools, I cannot see how that can be done without a considerable polarisation of the pupil mix as between white, black and ethnic communities compared to the present remarkably healthy balance," he said.
"I am therefore today writing in these terms to the Equality and Human Rights Commission asking for their ruling on this matter."
The public consultation centres on two options to reorganise schools in that area of Cardiff.
Option one could see the closure of Lansdowne Primary school and transferring Ysgol Gymraeg Treganna where two forms would be admitted every year.
The second option could mean the transfer of Lansdowne Primary school as a one-form entry school with nursery to Fitzalan High school and relocation of Ysgol Treganna on to the current Lansdowne site.
The consultation period will end on 27 February.