The warning from the Federal Office for Information Security comes after Microsoft admitted IE was the weak link in recent attacks on Google's systems.
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On Friday, Germany's Federal Office for Information Security issued a warning against all versions of Internet Explorer and recommended that users switch to an alternative such as Firefox or Google's Chrome.
The French agency Certa issued a similar warning.
"Pending a patch from the publisher, Certa recommends using an alternative browser," it said.
But Mr Evans said that calls to change browsers were "not very helpful".
"If you look at other browsers, it's likely they will have other vulnerabilities," he said.
He pointed to a report by security from NSS Labs reportedly showing that IE8 provided better security against phishing and malware than other browsers.
"We feel strongly that IE8 is most secure browser on the market," Mr Evans told BBC News.
His advice was echoed by Graham Cluley of security firm Sophos.
"Switching away will get away from this particular problem," he told BBC News. "But all browsers have security flaws."
Mr Cluley said that switching away from IE may create other problems, particularly for companies.
"Some web-based applications may not work at all if you're not using Internet Explorer."
Microsoft is currently working on a patch for the problem, but a spokesperson said it could not commit to a timeframe.
The firm traditionally releases a security update once a month - the next scheduled patch will be ready on 9 February.
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