Reese Witherspoon has confirmed 'Legally Blonde 3' is in the works.

The 42-year-old Hollywood actress revealed the news on her social media, accompanied with a clip paying homage to a classic scene of her character, Elle Woods, lounging in a pool in a pink sequinned bikini.

Reese teased fans of the forthcoming instalment of the much-loved romantic comedy franchise - which took $141 million at the global box office on an $18 million budget when it first hit cinemas 17 years ago - with the caption on Instagram: ''It's true... #LegallyBlonde3 [sic]''

The 'Big Little Lies' star played the ditsy blonde, who attempts to win back her high school boyfriend by following him to Harvard Law School, only to prove appearances can be deceiving when she aced her degree and became a top lawyer.

Not much is known yet about the plot for the sequel, but Kirsten 'Kiwi' Smith and Karen McCullah, who adapted the Amanda Brown novel for the original film, are in final talks to write the script.

Deadline's film editor Mike Fleming Jr, said: ''They are keeping the plot under wraps, but I'm told it will be much in the spirit of the first film.

''The intention here is to make this more about female empowerment, a message that hits at a fortuitous time in the culture.''

Marc Platt, who produced the original movie is returning with his Platt Productions president Adam Siegel, and will be joined by Reese through her production company Hello Sunshine, which boasts a reputation for celebrating women and ''puts them at the centre of the story''.

Popular rom-com director, Robert Luketic helmed the first film, but it is not yet known who will direct the third movie.