Kate Winslet and Leonardo DiCaprio starred as lovers Rose and Jack in the romantic-drama Titanic 20th Century Fox

It seems Rose really didn't let go of Jack as Titanic stars Kate Winslet and Leonardo DiCaprio were seen hanging out together during a reunion with their co-star Billy Zane, marking the movie's 20th anniversary.

Winslet, 41, and Zane, 51, showed their support for DiCaprio's environmental charity at the St Tropez Gala on 26 July. Much to the delight of Titanic fans, the trio realised the perfect opportunity to pose for a photo together exciting those who have longed to see the cast reunited after two decades.

Alongside the photo, Zane wrote: "Gang's back together. Now we're saving icebergs. Go figure," noting the irony of the gala's theme and the movie about the real-life "unsinkable" ship.

Zane's followers sent themselves into a frenzy over the reunion, with one commenting: "Literally the best thing in Instagram maybe ever."

Directed by James Cameron and released in 1997, Titanic was based on the 1912 disaster involving the RMS Titanic, which killed 1,517 people when it sank during its maiden voyage from Southampton to New York City.

Winslet played the young and affluent Rose who enjoyed a whirlwind romance with DiCaprio's Jack despite being promised to the older, wealthier and villainous Cal Hockley.

It is a special year for the cast of Titanic as the film is celebrating its 20th anniversary year. With fans still enamoured with the tear-jerking drama, director Cameron has announced a new documentary about the making of the film which is set to air on the National Geographic Channel.

In a statement, Cameron said of the documentary: "When I wrote the film, and when I set out to direct it, I wanted every detail to be as accurate as I could make it, and every harrowing moment of the ship's final hours accounted for.

"I was creating a living history; I had to get it right out of respect for the many who died and for their legacy. But did I really get it right? Now, with National Geographic and with the latest research, science, and technology, I'm going to reassess."

At the time of Titanic's release, DiCaprio was already an Oscar-nominated actor thanks to his work in What's Eating Gilbert Grape, but it is safe to say that Titanic propelled him to global stardom.

Reflecting on the epic blockbuster in 2016, the actor told Deadline: "Titanic was very much an experiment for Kate Winslet and I. We'd done all of these independent movies. I loved her as an actress and she said, 'Let's do this together, we can do this'. We did it, and it became something that we could've never foreseen."

Watch a scene between Rose and Cal from Titanic: