The announcement came as the streaming giant prepares to premiere the drama's third season later this month.

A Netflix spokesperson said the fourth season would feature "the core cast's graduation from High School, which will be a natural conclusion to the show".

The show's first series controversially showed one of its characters taking her own life.

Last month, Netflix announced the graphic scene had been removed "on the advice of medical experts".

Spoiler warning: the following reveals plot details from all three seasons of 13 Reasons Why.

Based on the novel by Jay Asher, the first season of 13 Reasons Why told of a high school student called Clay who finds out why his friend killed herself through a box of cassette tapes she recorded before her death.

The second season, which premiered last year, shifted the focus to other students at the fictional Liberty High School, among them an alienated teen planning a mass shooting.

A trailer for the third season poses the question "Who killed Bryce Walker?" - a reference to a student who was convicted of rape at the end of season two.

According to Netflix, the season will see Clay come under police scrutiny after Bryce disappears in "an investigation that threatens to lay bare everyone's deepest secrets".

When 13 Reasons Why launched in 2017, it was praised for promoting awareness of such issues as rape, bullying and self-harm.

But concerns were raised that it glamorised suicide and went into too much detail about how Hannah, played by Katherine Langford, killed herself.