John Howard says gun laws inadequate

John Howard, who introduced national gun control laws 20 years ago after the Port Arthur massacre, says the laws are inadequate and should be tightened.

Speaking on SBS' Insight program to Alpha Cheng, the son of NSW police employee Curtis Cheng who was fatally shot in Parramatta last year, the former prime minister said he would "encourage sensible strengthening of the existing laws".

"I would have thought that everybody would agree, if 15-year-olds can get hold of weapons like that, there is something wrong with the laws," Mr Howard tells the audience of Insight's episode on guns, which airs on Tuesday night.

"I'm not going to preach at the state government over this - they have to make a judgment about it. But I'm wholly against any watering down of the existing laws, and I would encourage sensible strengthening of the existing laws," the former PM said.

"Once you give people access to weapons and those people snap or exhibit a mental illness, then you will have tragedy," he said.

Mr Howard said he does not object to another firearms amnesty, but he has not been actively campaigning for one.

Mr Cheng, 58, was gunned down outside Parramatta Police Station on October 2, 2015, by 15-year-old schoolboy shooter Farhad Jabar, who was later fatally shot by police.