Two Hollywood stars have sworn to boycott the Oscars due to a lack of diversity in nominations.

Filmmaker Spike Lee and actress Jada Pinkett Smith both posted on social media saying they would not attend the February 28 ceremony, for which no African-Americans have been nominated.

The hashtag #OscarsSoWhite began trending online after several African-American Oscar hopefuls – including Beasts of No Nation’s Idris Elba, Creed star Michael B. Jordan and the cast of N.W.A biopic Straight Outta Compton – were snubbed.

• Inside Cate Blanchett’s stunning new English mansion
• Making a Murderer: the case for and against Avery
• Aussie George Miller wins Critics’ Choice Award

On the Martin Luther King national holiday, Lee said he and his wife “cannot support” the awards ceremony.

“How is it possible for the 2nd consecutive year all 20 contenders under the actor category are white? 40 white actors in 2 years and no flava [sic] at all,” the actor posted on Instagram.

He then quoted Martin Luther King: “There comes a time when one must take a position that is neither safe, nor politic, nor popular but he must take it because conscience tells him he’s right.”

When Lee accepted an honorary Oscar in Hollywood in November 2015, he also spoke about the lack of diversity within the industry.

“This industry is so far behind sports, it’s ridiculous,” Lee said during his acceptance speech.

“It’s easier to be president of the United States as a black person than be head of a studio. Honest.”

Jada Pinkett Smith also swore to not even watch the awards ceremony.

“I won’t be at the Academy Awards and I won’t be watching,” Ms Pinkett Smith said in a video posted on Facebook.

“Today is Martin Luther King’s birthday, and I can’t help but ask the question: Is it time that people of colour recognise how much power, influence, that we have amassed, that we no longer need to ask to be invited anywhere?”

“So let’s let the Academy do them, with all grace and love. And let’s do us, differently.”

But she congratulated African-American comedian Chris Rock on being appointed host of the event, saying she “can’t think of a better man to do the job at hand”.