Dustin Lance Black has called out Sam Smith for saying he was the first openly gay star to win an Oscar.

Tom Daley and Dustin Lance Black

Tom Daley and Dustin Lance Black

The 41-year-old screenwriter-and-director - who is engaged to Olympic diver Tom Daley - took to Twitter to correct the 'Stay With Me' hitmaker after he made the claim during his acceptance speech for his Best Original Song win for the 'Spectre' theme song, 'Writing's on the Wall'.

Standing at the podium at the ceremony on Sunday night (28.02.16), Sam said: "I read an article a few months ago by Sir Ian McKellen and he said that no openly gay man had ever won an Oscar.

"If is this case, even if it isn't the case, I want to dedicate this to the LGBT community all around the world. I stand here tonight as a proud gay man and I hope we can all stand as equals one day."

On Monday morning (29.02.16), Lance - who has long been out and proud and a champion of LGBT rights - tweeted Sam to let him know he was wrong and that was awarded the Best Original Screenplay prize for 'Milk' in 2009.

He also used his tweet to warn Sam not to message his partner Tom.

He wrote: "Hey @SamSmithWorld, if you have no idea who I am, it may be time to stop texting my fiancé. (sic)"

Dustin also sent him a link of him accepting his prize for the movie 'Milk'.

Alongside the clip, he wrote: "Here's a start."

Speaking after his win, Sam backtracked over his claim but insisted his speech was still important for equality for the LGBT community.

He told TV show 'Good Morning Britain': "I had something in my head, I read the Sir Ian McKellen thing. I think I am the second openly gay person to win it. But either way it is important that we shine a light on what is going on in the LGBT community because it is not right and there is a lot for us to work on in the world. And not just that, I feel like tonight was about diversity and equality in all different situations. It's important."