Katherine Langford explains why she couldn't return for 13 Reasons Why finale

Katherine Langford has revealed why she could not return for the final season of 13 Reasons Why on Netflix, the series that launched her to international stardom.

The actress played Hannah Baker in the first two seasons of the teen drama, a teenage girl who tragically commits suicide for reasons that are gradually revealed as the story unfolds.

She did not appear in the third season, but fans had speculated she may film a brand new cameo for the fourth and final instalment, which landed on Netflix earlier this month.

Langford has revealed that this was not possible due to scheduling conflicts with her new series Cursed, a fantasy drama loosely based on Arthurian legend.

"I think I was still filming Cursed, so I wasn't able to go in and shoot anything," she told Digital Spy and other press. "It's funny because I haven't fully seen season three or four – but I'm making my way through season three and watching season four now that that chapter's closed.

Langford added: "I'm really proud of everyone in the cast, and we're still really tight. In many ways, I already know what happens and I'm just so proud for them. Closing that chapter was such a special part instilled in all of our lives."

Rather than film any new Hannah Baker scenes, producers used archive footage from the first season to insert her into the finale, giving some added closure to the story of troubled high school student Clay (Dylan Minnette).

13 Reasons Why is streaming now on Netflix. Check out our lists of the best TV shows on Netflix and the best movies on Netflix, or see what else is on with our TV Guide.