ElementTree and unicode

I have this char in an xml file:

<data><products><color>fumè</color></product></data>

I try to generate an instance of ElementTree with the following code:

string_data = open('file.xml')x = ElementTree.fromstring(unicode(string_data.encode('utf-8')))

and I get the following error:

UnicodeEncodeError: 'ascii' codec can't encode character u'\xe8' in position 185: ordinal not in range(128)

(NOTE: The position is not exact, I sampled the xml from a larger one).

How to solve it? Thanks