Lady Gaga is set to take part in a gay pride parade in Rome's Circus Maximus - the closing event of 2011 Euro Pride.
The US Ambassador to Italy David Thorne said in a statement that he was "very proud to have an Italian-American artist of her stature" come to the Italian capital.
He also quoted US Secretary of State Hillary Clinton as saying human rights are gay rights.
Gaga was invited by David and the local organisers of Euro Pride, which takes place each year in a different European city.
The Poker Face singer's new album Born This Way recently sold a million copies in its first week.
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