Plaid Cymru leader Adam Price has said he is "profoundly" sorry if his use of the term reparations "caused pain".
It follows a speech he made last year calling for Wales to be compensated by the UK for being "ground down" into "poverty".
Labour's Health Minister Vaughan Gething said the language was "deliberately offensive" terminology.
Speaking to BBC Radio Wales on Sunday, Mr Price apologised for his "poor choice of words".
He said that since his speech, he had learnt the black and minority ethnic (BAME) community feel strongly that the term 'reparations' should only be used in the context of compensation in relation to the slave trade and western colonisation.
"We were both a victim of colonisation but we've also been a perpetrator, and that hasn't been sufficiently foregrounded I think in the story that we tell about ourselves," he told the Sunday Supplement programme.
Asked whether it was appropriate to compare colonialism and slavery to the Welsh experience, he said you cannot equate suffering or injustice in one place to another.
"If I've caused pain by my poor choice of words, I'm profoundly, deeply, genuinely sorry for that," he said.
"We have not sufficiently accepted our guilt and complicity in one of the most murderous human enterprises in history which is the British Empire, and the fact that we have in Wales, as a western country, have also benefited from the wider European colonial project," he added.
"We have to honest about our own past and our own complicity and the fact that we have suffered injustice as well.
"It's important that we don't erase that because that is part of our history too but we must also recognise and reckon with our own contribution to suffering and injustice in the past and by the way recognise the realities of injustice and oppression within Wales today - the fact that we have structural racism at the heart of our society."
You can listen to the full interview and the rest of the BBC Radio Wales Sunday Supplement with Vaughan Roderick on the BBC Sounds app.