Mr Brown first heard of the discovery of cancer-causing dioxins in animal feed on 30 May, when he was told by the European Union's Agriculture Commissioner, Franz Fischler, during a summit in Dresden.
He said his department knew on 28 May and officials immediately set about contacting the industry, particularlyimporters from Belgium.
A spokesman stressed later that the Food Safety Minister, Jeff Rooker, had been informed of the scare immediately.
Mr Brown announced that he had made two emergency orders under the Food Safety Act, giving full legal effect to decisions by the European Commission banning the export or sale of certain Belgian products.
"The UK Government believes firmly that the Belgian government should have acted earlier to inform trading partners of the problem ... it was a scandal that the information was withheld," Mr Brown said.
"Feed contamination is believed to have occurred over a period of less than six months and Belgian food in the affected categories represents a very small proportion of total UK consumption," he added.
But a decision by some non-EU countries, including the US, Canada and Singapore, to restrict imports of products from throughout the EU was "disproportionate". "There can be no basis on food safety grounds for such action and it is deeply unfair to our domestic producers," Mr Brown said.
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