TORONTO -- Security ministers from the G7 countries are discussing how to fight the threats lurking in the internet's dark spaces against the backdrop of a city reeling from Monday's deadly daylight van attack.

Public Safety Minister Ralph Goodale was peppered with questions and offers of assistance from his G7 counterparts after Monday's tragedy, in which a rental van barrelled through a crowd of people on a north Toronto sidewalk, killing 10 pedestrians and injuring 15.

A major focus of the final day of the G7 ministerial meeting in Toronto was addressing violent extremism and preventing the internet from being as a tool for training, propaganda and financing.

"It's the insidiousness of the messaging on the web," Goodale said in an interview ahead of Tuesday's talks.

"That's something that all ministers worry about."

Goodale and his fellow G7 leaders will be calling on major internet service providers that are also at this meeting -- Google, Facebook, Twitter and Microsoft -- to do more to prevent their platforms from being exploited.

Goodale said the service providers realize the need to co-operate, and will be discussing options with the G7 ministers. He said they will be urging service providers "to be quick and proficient, and quick and persistent in making sure their various services are not any kind of platform for terrorist material or terrorist activity."

"You do not want your platform to be known as a safe harbour for terror or sexual exploitation or human trafficking or political interference."

In Tuesday's opening remarks, Goodale said cybertechnology has become "a disruptive force" with the potential to harm critical infrastructure "and the power to more easily conceal identities."

In the interview, Goodale offered some insight into the closed-door discussion he planned to lead with his counterparts.

"The one question that would always bother me is: is there anything we're missing?" he said.

"You're looking for the holes. When you're dealing with this technology and you get into the deep, dark web, how much of it is encrypted, how much of it is inaccessible, how much of it is beyond technical capacity to crack into."

But there are thorny ethical issues at the heart of that discussion, the minister cautioned.

Goodale cited the recent controversy that has placed Facebook at the heart of a major scandal over the inappropriate use of its data in the United Kingdom's Brexit campaign and Donald Trump's successful U.S. presidential bid.

"The latest controversy about Facebook actually puts this whole set of issues in stark relief," he said.

"On one side, everyone is agreed that we need to collaborate and fight hard to combat child pornography, human trafficking, political interference and terrorist content on the web.

On the other hand, he said the recent Facebook controversy placed privacy concerns front and centre.

The ministers also discussed how to guard against ongoing domestic threats. Though nothing has emerged so far to link Monday's events in Toronto to extremism, the use of a vehicle as a weapon against pedestrians is something that Goodale's British, French, American and German counterparts are all too familiar with.

Goodale reiterated that no motive for Monday's van attack has been found to link it to a national security threat, but he said the Toronto police investigation remains in its early stages.

"We've witnessed brutal terror attacks on our own home soil, and attacks on our democracies through foreign interference during elections," Goodale told his fellow ministers Tuesday.

"These tests to our collective security demand our constant collaboration through the G7."