Dafydd Elis-Thomas fired from Plaid Cymru roles
Plaid Cymru has fired former leader Dafydd Elis-Thomas as transport spokesperson and chair of the assembly's environment committee.
It follows his criticism of leader Leanne Wood's attack on UKIP at the party's spring conference.
The former assembly presiding officer said it was "facile" of Ms Wood to say a vote for UKIP is a vote against Wales.
He said he may challenge his removal as environment committee chair.
Lord Elis-Thomas told BBC Wales the current system where committee chairs are nominated by the political parties undermines the system's independence.
In a statement on Thursday confirming the sacking, Ms Wood said: "Plaid Cymru sought over the weekend to highlight the dangers posed to Wales by UKIP, because we fundamentally and sincerely believe that their politics and policies are not in the best interest of the people of our communities.
"Dafydd Elis-Thomas decided to publicly oppose this position without raising any concerns in advance.
"The people of Wales, and Plaid Cymru members, expect and deserve a national party that is united in addressing the challenges our country faces; on jobs, the economy and will continue to put Wales first."
The row was sparked on Friday in a speech to Plaid's spring conference from Ms Wood, referring to UKIP and May's European election, in which she said: "Your politics have no place in our country, not now, not ever.
"Your values are not the values of Wales. A vote for UKIP is a vote against Wales - a vote against the Welsh national interest. We cannot and will not let their ugly politics divide us in May."
UKIP criticised Ms Wood's attack as "gutter politics and mudslinging" and her comments also drew criticism from Lord Elis-Thomas.
Speaking last Saturday he said: "It is facile and assumes a kind of superiority that we decide who is Welsh and who is not Welsh.
"A party which gets votes from ordinary citizens in Wales has to be taken seriously. It clearly represents a point of view in Wales."
Speaking to BBC Wales on Thursday, Lord Elis-Thomas said his criticisms were not directed so much at what Ms Wood said in her conference speech, but at the wording of a briefing and press release earlier in the week in which the expression "un-Welsh" was used.
He said: "I don't know what the word 'un-Welsh' means, because sitting in this assembly we emphasise equality, we emphasise this place belongs to all the people of Wales.
"And therefore you don't start calling your fellow citizens, your colleagues in Wales, names even if they are in a party with which you disagree."
Lord Elis-Thomas said he would consider over the weekend whether he would oppose the motion to replace him as chair of the assembly's environment committee.
"It would give us an opportunity to raise the issue in public and explain to the people of Wales that AMs are more gagged and have less of a democratic scrutiny within their party system than happens even in Westminster," he said.
It is understood that Lord Elis-Thomas met Ms Wood on Wednesday night to discuss his comments, which led to his sacking from his roles.
Alun Ffred Jones will be Plaid Cymru's nominee for chair of the environment committee while Rhun ap Iorwerth will become the party's transport spokesperson.
Lord Elis-Thomas was previously threatened with disciplinary action by the party in 2012 after he failed to attend an assembly vote on health policy, although on that occasion the party backed down.