London Bridge: Boris Johnson accused of 'trying to exploit' attack
The prime minister has been accused of "trying to exploit" the London Bridge terror attack "for political gain".
Plaid Cymru candidate Jonathan Edwards said some of Mr Johnson's comments were "pretty shallow."
But Tory David TC Davies said it was right to review the early release of those convicted of terrorism offences.
Labour's Lord Peter Hain raised concerns about the parole system, while Welsh Liberal Democrat leader and candidate Jane Dodds and the Brexit Party's Nathan Gill paid tribute to the victims.
Jack Merritt, 25, and 23-year-old Saskia Jones were killed and three others injured in the attack which was brought to an end when police shot Khan dead.
Speaking on BBC Radio Wales' Sunday Supplement programme, Mr Edwards said: "I think some of the comments of the prime minister this morning, unfortunately, is pretty shallow.
"He's trying to exploit the situation for political gain.
"He's trying to hide away from the very poor record of the Conservative Party over the last 10 years with the cuts that they have made and when the cuts are made in these areas these incidences, unfortunately, become more likely to happen."
No 10 has been approached for a comment.
Khan, 28, was jailed in 2012 after he plotted with a group from Cardiff, London and Stoke-on-Trent to bomb the London Stock Exchange.
In 2012, he was sentenced to indeterminate detention for "public protection" with a minimum jail term of eight years after pleading guilty to preparing terrorist acts.
The sentence would have allowed him to be kept in prison beyond the minimum term, should the authorities have deemed it necessary.
But in 2013 the Court of Appeal quashed the sentence, replacing it with a 16-year-fixed term of which Khan should serve half in prison. He was then released automatically.
Mr Johnson told the BBC's Andrew Marr programme 74 people jailed for terror offences and released early will have their licence conditions reviewed.
Mr Davies, Conservative election candidate, said: "I don't think the prime minister is trying to make any political capital out of this, others have chosen to do that.
"Obviously there has to be an inquiry into this but the police were there very, very quickly.
"But there does need to be a discussion, first of all, about early release… and secondly on the importance of supporting the police and the armed forces, whether it's on the streets of London or in the deserts of Syria or Iraq.
"Our security forces need to be able to take whatever action is necessary and that may mean shooting people in order to keep us safe and we need a prime minister who is willing to support that."
Former Labour Welsh Secretary Lord Hain said it was important to support the police and not give "knee-jerk responses".
He added: "I think when we pore over the details of how all this happened and how this horror occurred, you cannot administer justice on the cheap - I think that's one of the key lessons we need to draw from this terrible attack."
Ms Dodds said: "There just needs to be a step back from this and the emotion taken out of it and just see it for what it is - an incredibly tragic, upsetting event that led to the lives of two people being lost."
Mr Gill added: "I think what we saw on Friday was pretty much the best and the worst of mankind.
"We've seen somebody who is fuelled by hate doing something absolutely terrible… but also we saw the bravery of mankind as well."