Leanne Wood, leader of Plaid Cymru has said she is “staggered” by the response to her suggestion that the Barcelona attack was “far-right” terrorism.
She added: “All forms of political violence are the same. USA, Barcelona, everywhere. They are ideology-driven & we have to understand that to stop it.”
A Welsh Conservative Assembly member called on Ms Wood to apologise or resign, while UKIP accused her of an “outrageous smear”.
Ms Wood said: “I am staggered by the reaction to the point that Isis and white supremacism both have far-right ideologies driving them.
“Both see their group as superior to others. Both see people who are not in their group fair targets for abuse, violence and even death.
“I can see why this point may upset so many trolls and people who see themselves as being on the far right.
“The comparison links western racists and white supremacists to their number one hate target and shows them as no better than each other.
“Events in Barcelona last night were terrifying, yet again.
“While it’s important, in my view, to say and keep saying that politics and ideology lie behind these acts of violence, my thoughts are first and foremost with the victims of last night’s horror.“
Welsh Conservative leader Andrew RT Davies described Ms Wood’s original comments as “unbelievable” and later tweeted: “I’m staggered that she’s staggered.
He had earlier said: “Sickening to hear of the attack in Barcelona. We will stand together and prove that our values will prevail and hate will never win.“
His colleague Janet Finch-Saunders AM said: “She should apologise and withdraw those unacceptable comments or resign.“
Meanwhile, Ukip in Wales tweeted: “Absolutely outrageous smear by Leanne Wood who uses ‘far right’ to describe Ukip. How dare you associate us with murderers.“
He said: “It is truly horrifying to think that people who were simply going about their daily lives, relaxing and enjoying themselves could be targeted in such an evil way.
“Barcelona is a proud and beautiful city which welcomes international visitors with open arms, including many from Wales.“
“We stand by your side at this difficult time.“