Kirsten Dunst was "making out all night long" with her new boyfriend.

The Melancholia actress has been rumoured to be seeing actor Garrett Hedlund for months now, but she has not spoken publicly about their affair.

Kirsten reportedly removed all doubt about her relationship with Garrett while partying at Tao on Monday.

The pair were getting very close to one another throughout the night at the club.

"[Kirsten and Garrett] were making out all night long," an eyewitness told RadarOnline. "They were attached at the hip the whole night and it was obvious to everyone that they were an item."

Kirsten and Garrett have been spending a lot of time together recently.

Garrett accompanied the actress to the premiere of her newest film Bachelorette, which screened at Sundance earlier this week. He and Kirsten sat next to each other at dinner with her castmates before the showing.

Kirsten has enjoyed previous relationships with Jake Gyllenhaal and Razorlight musician Johnny Borrell.

Garrett shot to fame in his breakout role in the 2004 action feature Troy and will next be seen in the film adaptation of Jack Kerouac's novel On the Road.

The pair are thought to have been dating since late last year.