The Polish ambassador to Sweden has reported Uggla to the Ombudsman against Ethnic Discrimination for a line from his song 'For King and Country'.
Part of the song deals with the issue of Swedes renovating their homes with the help of tradesmen who are paid off the books.
"If my wife and I get a little bored, we call up a dodgy Pole," sings the 52-year-old star.
The Polish ambassador resented the implication and requested that the singer remove the reference.
Uggla instead exacerbated tensions at a rehearsal last week. Having been handed 120 kronor by the show's presenter, the singer unleashed a fresh invective.
"I'll buy Poles with the money," he said.
Poland's Vice Consul reacted strongly to the comment.
"Of course it is discrimination," said Agata Kardas.
"The absolute majority of Poles in the country work hard and behave themselves," she added.
Rather than taking the criticism seriously, Uggla continued to provoke.
"There are Poles standing at every street corner waiting to be called into action," he said.
On Thursday the Polish embassy decided that it had heard enough and reported the singer for discrimination.
The embassy also addressed a letter of complaint to national broadcaster SVT.
"We haven't yet decided how we are going to reply. We will respond on Friday morning at the latest," SVT's Hans Hernborn told Expressen.
The Polish Congress in Sweden has advised people not to vote for Uggla, while Warsaw-based news agency PAP has asked requested an explanation from Melodifestivalen's organisers, Expressen reports.
Magnus Uggla announced via his press secretary that there are no plans to make any changes to the song, which is due to be performed at the semi-final round this Saturday.