Rolling her eyes, she told talk show host Jimmy Kimmel on Wednesday: "People saw love, and guess what, that's what we wanted you to see."

During their performance of Shallow, they gazed lovingly at each other and ended up together at the piano.

She said: "I'm an artist, I guess we did a good job - fooled ya!"

The singer won the Oscar for best song for Shallow, from the film A Star Is Born, at Sunday's ceremony. Cooper starred in and directed the movie.

Kimmel said to her: "People started saying, 'Oh, they must be in love'. We were watching it at home, we were going, what's going on between these two?"

Lady Gaga's response was typically blunt, saying: "First of all, social media, quite frankly, is the toilet of the internet. And what it has done to pop culture is abysmal.

"This is a love song... the movie - it's a love story. We worked so hard, we worked all week on that performance."

She said it had been important to both herself and Cooper "that we were connected the entire time".

Their performance was entirely "his vision", including the lighting on the audience throughout the performance.

The singer joked: "Look, I've had my arms wrapped around Tony Bennett for three years touring the world. When you're singing love songs, that's what you want people to feel."