The former Labour prime minister took aim at the “America first, India first, China first” actions of governments and called for international intervention to fight the pandemic.
Mr Brown, who was in office during the 2008 financial crisis, said the scale of the crisis now facing the country was “unprecedented” and urged the chancellor Rishi Sunak to do “considerably more” to protect people from financial ruin.
His intervention comes as schools and nurseries prepare to close, with the army placed on standby and the prospect of greater restrictions in London to curb the spread of the virus.
“This is a global problem, not just a national problem,” Mr Brown told BBC Radio 4’s Today programme.
“We’ve had too much of America first, India first, China first. We have had too much of this populist nationalism.
“We are finding that we are connected whether we like it or not. We are finding that we are depending on each other whether we like it or not.
“I think people have got to put aside the differences they have, as international cooperation is absolutely vital for this.”
The former chancellor said the outbreak was a “global economic emergency” as well as a public health disaster, leaving people “doubly afraid”.
“They’re afraid of catching the virus, or their family members catching the virus, and they’re afraid of their livelihoods and their family incomes being lost,” he said.
“And we’ve got to act on both fronts and we’ve got to act domestically and we’ve got to act internationally.”
Mr Brown urged ministers to do much more to protect workers, adding: “If Boris Johnson tells people to go home and to stay at home, he has got to tell them how they are going to be able to survive financially.”
“I think [Rishi Sunak] will have to do considerably more to deal with the issues of employment protection,” Mr Brown said.
“He says he’ll do more but the package should be out now to avoid redundancies being forced upon companies over the next day or two.
“I think a lot of company directors will be looking at the moment to how many staff they are going to shed in the next few days, next few weeks.
“And I think we need to step in now with building the confidence that we can keep people in work or keep people on short term in work and have an arrangement with people where they take some holidays but at the same time they are going to have income protection.
Workers needed to be able to return to their jobs once the pandemic is over, he said, adding: “My fear is we have not done enough to do that.”
Mr Brown said the American approach of handing out money was “scattergun”, as US millionaires like Donald Trump “don’t need a cheque”.
Amid growing speculation that London could be locked down, Mr Brown said the government should have “acted a bit more quickly” but admitted he did not have the full information.
“I think people have got to accept that at certain points, as we’ve done before, we bring in the army to help us in certain respects.
“I’m not advocating greater legal sanctions but I am advocating using all the resources of this country.”
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