Chris Colfer says his version of 'Baby, It's Cold Outside' on 'Glee' was "the gayest thing that has ever been on TV".

The actor's character Kurt Hummel performed a duet of the song with

Darren Criss - who plays his love interest Blaine in the musical TV show - in the episode 'A Very Glee Christmas' and he believes the performance pushed the boundaries of what's been shown on television before.

Chris said: "That was by far the gayest thing that has ever been on TV, period."

The festive track has become the most downloaded off the 'Glee' Christmas album.

Chris has spoken about his on screen relationship with his co-star, saying he loves the positive support the show's fans and the public have shown them as they've got over the initial shock of a high-profile gay relationship.

He added to Entertainment Weekly: "When we made the announcement that Kurt was getting a boyfriend, people went bats, they were so excited, and then you add Darren, who is incredibly talented, people are just jumping up and down.

"It's become less and less about the obvious frame of it, the young teen gay couple on the popular network show.

"It's more about just a favourite character having a love interest, which is awesome."

'Glee' creator and executive producer Ryan Murphy added he was very pleased with seeing the couple's relationship on screen.

He added: "I was proud of that. I think it pushed the envelope a bit."