Theresa May should take responsibility if Britain has been too soft on extremists, the leader of Plaid Cymru has said.
Leanne Wood made the comments in a BBC TV debate, which took place a day after the terrorist attack in London.
Ms Wood also said that she would like to see the highest tax rate raised from 45% to 50%.
She said she would be willing to put up taxes to fund public services.
Referring to the prime minister's speech in the wake of the attack, where she said there had been "far too much tolerance of extremism in our country", Ms Wood pointed to the fact that Mrs May had been home secretary for six years prior to being prime minister.
"Since 2010 she has been in a position to do something about this," she said.
"And if we have been too soft on extremists as she claims, then doesn't she need to take some responsibility for that?"
Speaking on Election Questions on BBC One, Ms Wood said Plaid "would be open to a discussion" about putting income tax up for higher earners in Wales, once powers are devolved.
"For those who can afford to pay the most we would," she said.
Pushed on the subject again if, "in principle", she would put tax up in such a way, she said: "For the additional rate of income tax people who currently pay 45%, we would like to see that go up to 50%.
"That would bring in a British context £3bn extra to spend on public services."
But she qualified that by adding: "When income tax comes to Wales we will be having a different conversation."
Income tax varying powers could devolved to the assembly from 2019.
Asked if it would be the time to trigger a campaign for independence if there was a "very hard Brexit", she said: "It may well be".
"If that final deal is going to be very bad for Wales then we need to consider all options at that time," she said.