Broadcaster Alan Jones has sparked an online backlash after suggesting radical students planted the Boston bombs and Australia should take more care letting in foreign students.
Jones appeared on the Seven Network on Wednesday morning to say such an attack could happen in Australia.
The bombings near the finish line of the Boston Marathon killed three people and injured more than 170.
"I think what we have to remember about Boston is that it's a student city, you've got Harvard, MIT (Massachusetts Institute of Technology) and a stack of other colleges," he said from his 2GB studio.
"I wouldn't be surprised if this was a conspiracy among students, left-wing radical students in Boston, and I think we have to think also very seriously here about our own student numbers.
"We are very keen to have foreign students pay the way of universities in this country without a lot of discernment about who comes in," Jones said.
Former NSW treasurer Michael Costa, who also appeared on Seven's Sunrise show segment, responded to Jones's comments, saying people shouldn't "jump to conclusions yet about what's behind all of this".
"Let the American authorities deal with it," he said.
Critics of Jones took to the microblogging site Twitter.
One wrote that Jones was trying to make a "cheap domestic political point out of Boston slaughter" and another tweeted "Prejudice, speculation & fear should not be used to fill airtime".
Political commentator George Megalogenis tweeted, "Alan Jones can see the Boston bomber/s from the 2GB studios".
Jones was widely criticised and had to apologise last year after saying at a Liberal Party fundraiser that Prime Minister Julia Gillard's late father had "died of shame" over her "lies".