Niall Horan has slammed a group of "abusive" fans who have been sending the pop star inappropriate messages around the clock.

The Irish singer is currently enjoying an hiatus from his post in One Direction but he continues to interact with his over-25 million followers on Twitter, even though some of them have started becoming abusive.

Niall decided enough was enough on Tuesday (24May16), revealing a select group of foul followers had been inundating him with negative and disturbing messages, including inappropriate tweets about members of his family, in recent weeks.

In a raging series of tweets, Niall wrote: "For the last two weeks I've been receiving messages off a group of fans (sic), they have drowned my phone in messages, keeping me awake at night. But the worst part is. They have been nothing but abusive. Saying things you wouldn't even believe about me and my family.

"And saying the worst things ever about my little nephew. Thank god I'm not the kind of person who thinks into stuff like this. But I just think it's crazy how we let people (get) away with things like this. And the sad thing is. As I tweet this they are in the group chat laughing at me."

Niall, 22, assured his less aggressive fans he won't be letting the rude followers ruin his positive attitude, concluding, "Don't worry about me. im the most carefree, laid back person around. But I'm just signaling it, because this s**te is happening to others."

Shortly after Niall called out the Internet trolls, his supporters stormed social media with messages of encouragement, and the hashtag #RespectNiall became the top worldwide trending topic on Twitter.

It's not the first time the pop star has taken aim at extreme fans - last year (15), before One Direction announced their hiatus, he urged devotees to stop risking serious injuries by chasing the boy band's cars on motorways, autobahns and freeways - because it terrifies him and his bandmates.

The Drag Me Down singer told the BBC the worst thing about fame is watching people risk death just to get a photo.

"We've been chased down the street and on the motorways at 70 miles an hour, and surely that's not safe...," he said. "They're (fans) hanging out of windows... (and) switching lanes. They're going fast and it's quite scary."