Daniel Radcliffe Kissing Co-Star: Erin Darke New Girlfriend? (VIDEO)

Daniel Radcliffe and co-star Erin Darke have been growing closer and could be developing a relationship, according to some sources this week.

Darke and Radcliffe made a recent appearance at the Grey Goose Blue Door in Park City, Utah, along with other cast members from "Kill Your Darlings." While at the party, the couple was seen spending a fair amount of time with one another, and reportedly kissed, according to People magazine.

The couple also separated from the crowd with another couple.

Witnesses at the party confirmed that Darke appeared to be Radcliffe's girlfriend. However when Radcliffe was asked about whether or not he was dating Darke, he allegedly avoided the question.

"Erin? Oh, Erin Darke?" he told People in response to the question. "Yeah, the whole cast is here. It's fantastic."

Radcliffe split with his former girlfriend, Rosie Coker, last October. The two began dating in 2011, four years after they first met while on the set of Harry Potter. Coker was a production assistant. The couple split while Radcliffe was filming "Kill Your Darlings" with Darke.

A separate source said that Radcliffe and Darke had been together for a while. The source confirmed, "They've been seeing each other," according to Us Magazine.

Here is a video of "Kill Your Darlings" at the Sundance Film Festival: