US President Donald Trump often tries to "create chaos" when he opens his mouth, Oscar-winning director Frederick Wiseman said Wednesday.
The veteran American famous for his painstakingly detailed documentaries on the country's institutions, lashed out at Trump as his latest, "City Hall", was premiered at the Venice film festival.
Wiseman, 90, followed Boston's Democratic mayor Marty Walsh and his team for the best part of a year.
The resulting four-hour film has been hailed as "a testament to American democracy" when so many of its tenets seem to be under threat.
"Mayor Walsh and Trump represent two extremes," Wiseman told reporters.
"Every time Trump opens his mouth he says something idiotic which is either racist or divisive, or with the intent to create chaos.
"Someone like Mayor Walsh is interested in bringing people together and negotiating and finding ways of resolving problems," said the director, who was born in Boston but now lives mostly in Paris.
Wiseman said his sprawling portrait of local authority is "an example of democracy functioning.
"Does it function perfectly? Obviously not but I do not know any form of government that does," he added.
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