Dunst and Hartnett have been spotted together on and off for years.
Now, rumours of their on-again romance are circulating after the two stars shared dinner together at Blue Ribbon Sushi in New York. "They were whispering and smiling at each other. At times it looked like she wanted to grab his hand, but stopped," said a witness.
The two stars met while working on the film The Virgin Suicides in 1991. They were spotted together at the Sundance Film Festival last year, and again at a nightclub in New York.