Prime Minister Malcolm Turnbull insists that a deadly poison gas attack which killed at least 70 people in Syria is a war crime and “cries out for a strong response”.

But his government won’t be drawn on whether Australia would consider joining potential US action against Syrian President Bashar al-Assad if asked by the Trump administration.

“As a parent, a grandparent, everyone weeps when you see this sort of inhumanity, this cruelty,” Mr Turnbull told 3AW Radio on Friday.

“We have condemned this attack utterly. It cries out for a strong response.

“It is horrifying. This is a war crime of the worst sort. It is inhuman and it has been universally condemned,” he said.

Mr Turnbull said Australia had been in close touch with its US ally, and he has discussed the issue with Defence Minister Marise Payne and the defence force chief.

“I don’t want to speculate any further,” he said.

“You know where we stand. We condemn this attack utterly. It cries out for a strong response and we are in close touch, as we always are…close and constant communication with our allies and in particular the United States,” Mr Turnbull said.

He said there did not appear to be any doubt the Syrian regime was behind the attack despite their denials.

“There does not appear to be any doubt…I know that they assert that they are not but the American assessment – which is shared by America and her allies – is that this was an action by government forces,” he said.

Australia has conducted some air strikes in Syria as part of its contribution to the fight against Islamic State extremists in the Middle East.

US Vice-President Mike Pence upped his criticism of the Assad regime in the wake of this week’s deadly gas attack in northern Syria, telling US media “all options are on the table”.

Asked if Australia would join any US action without UN backing, Defence Minister Marise Payne told ABC radio on Friday.

“We’ll make decisions in regard to those sorts of issues as they are brought to us,” she said.

Senator Payne said the most important thing now is to condemn the attack.

“We have to be clear with Russia, we have to be clear with those who support the regime that this is totally unacceptable,” she said.

The minister said Australia would “of course” be part of the conversation about possible US action.

— with AAP