The Academy of Motion Pictures Arts & Science which organises the Academy Awards is reportedly scrambling to find a host for the 2019 ceremony after Kevin Hart stepped down amid controversy over homophobic tweets from his past.

According to US entertainment industry website Variety, there were no contingency plans in place by the Academy or broadcaster ABC and the producers are now back to square one.

The website reports that the Academy is currently exploring options, which includes going without a host and another using several celebrities to co-host the ceremony.

Two insiders told Variety that the Academy was "blindsided" by Hart's departure last Thursday.

Hart chose to withdraw as the host instead of apologising for tweets which were from nearly a decade ago.

"I chose to pass on the apology. The reason why I passed is because I've addressed this several times," the 39-year-old said in a video posted to Instagram. 

"I've said who I am now versus who I was then. I've done it. I'm not going to continue to go back and tap into the days of old when I've moved on and I'm in a completely different place in my life."

On Twitter, the Jumanji: Welcome to the Jungle star struck a more conciliatory tone, saying: "I sincerely apologize to the LGBTQ community for my insensitive words from my past."

The Academy is under pressure to solve the host problem ahead of the 91st Academy Awards ceremony on February 24, 2019.

Previous host Jimmy Kimmell hosted the gig for two consecutive years.

Whoever hosts it will face pressure to boost audience ratings for the annual show which had an all-time low of 26.5 million viewers last year, compared to 43 million in 2014.