Shawn Mendes has declared he's heterosexual.

Shawn Mendes

Shawn Mendes

The 17-year-old singer - who was rumoured to be dating Fifth Harmony singer Camila Cabello - clarified his sexual orientation in a video posted on his Snapchat account and said he was responding to comments made online that he emits a "gay vibe".

In the video posted on the photo and video sharing app, he said: "So I don't usually do this and bring up problems, but I was on YouTube just watching some of my interviews, and I was going down the comments and noticed a lot of people were saying that I gave them a 'gay vibe'.

"First of all, I'm not gay. Second of all, it shouldn't make a difference if I was or if I wasn't. The focus should be on the music and not my sexuality."

The heartthrob went on to urge fans who are quick to "judge" to think before they comment on a person's attributes.

He added: "Now I know 99 percent of you guys aren't making assumptions like this, but this is just for the one percent of you that are. I just want you guys - before you judge someone on the way they speak or act - I want you guys to think, 'Hey, maybe I shouldn't be judging someone' or 'Wait, it actually doesn't even matter. They can do or be or feel however they want to feel.'"

Meanwhile, Shawn was forced to deny he's dating 19-year-old Camila after they oozed chemistry in the music video for 'I Know What You Did Last Summer'.

And speaking about working with her pal, Camila previously said the rumours have no effect on her.

She said: "When it comes to Shawn the speculation doesn't really bother me because we're just really great friends. But if I could give any advice to girls that get hate when they have close friendships with a guy is that at the end of the day, all that matters is that you surround yourself with people that make you happy and if people around you hate on you for that, then they're not really people you want in your life anyway."