Welsh Labour politicians have expressed support for Plaid Cymru leader Leanne Wood's suggestion that the Barcelona attack was "far right" terrorism.
Thirteen people died when a van drove into pedestrians in the Spanish city, with so-called Islamic State (IS) saying it was responsible.
The Welsh Conservatives had called on Ms Wood to apologise or resign.
But Counsel General and Labour AM for Pontypridd Mick Antoniw said she had "nothing to apologise for".
Mr Antoniw tweeted: "Isis is a right wing extremist, fundamentalist ideology Your description is right. There is nothing to apologise for."
Commenting on his tweet, Labour's Swansea East AM Mike Hedges tweeted his agreement, saying the right wing had "many faces".
People from 34 different countries were injured or killed in the attack on the famous Las Ramblas on Thursday.
Hours later, police killed five suspected jihadists in a second vehicle attack in the town of Cambrils. A woman injured in that attack died later, taking the total death toll to 14.
Following the Las Ramblas attack, the Plaid Cymru leader posted her reaction on Twitter, saying: "Ofnadwy / terrible. Is this more far right terrorism? My thoughts are with all those affected."
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."
The comments sparked a critical response from politicians of other parties and on social media.
But Ms Wood has said she was "staggered" by the response, saying far-right ideologies drove both IS and white supremacists.
Welsh Conservative leader Andrew RT Davies, who had tweeted it was "sickening" to hear of the attack in Barcelona, said it was "unbelievable" Ms Wood had speculated it might be linked to a far-right group.
A tweet from UKIP Wales said: "Absolutely outrageous smear against UKIP which you have called 'far-right' countless times. How dare you associate us with murderers!"
Ms Wood responded on Facebook, saying: "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. Both hate minorities and consider women to be less than men.
"Both believe in using extreme violence to repress people with different views. This is far right/ fascism ideology. How can it not be?"