Diving star Tom Daley has said he "couldn't be happier" after revealing he is in a gay relationship.

The Olympic medallist posted a video on YouTube in which he said his life had "changed massively" since he began dating a man earlier this year.

"I've never really had a serious relationship to talk about," he said.

"Now I kind of feel ready to talk about my relationships.

"Come spring this year, my life changed massively when I met someone and it made me feel so happy, so safe and everything just feels great. And that someone is a guy."

The 19-year-old, who has faced questions over his sexuality in the past, admitted the relationship had taken him "by surprise a little bit".

"It was always in the back of my head that something like that could happen, but it wasn't until spring this year that something just clicked," he said.

"It felt right. My whole world just changed, right there and then.

"Of course I still fancy girls. But I mean, right now I'm dating a guy and I couldn't be happier. It makes me feel safe and just really does feel right."

Daley, whose father Rob Daley died in May 2011 following a battle with brain cancer, added: "People will think 'What will your dad say?' or 'What would your dad have said?'. He always said to me 'As long as your happy, I'm happy', and right now I couldn't be happier."

The teenage sports star posted a link to the video to his 2.4 million Twitter followers, with the message: "Got something I need to say...not been an easy decision to make, hope you can support me!"

In the clip, Daley said friends and relatives he had spoken to about his relationship had been "so supportive", although there were "mixed opinions" from some family members.

"Lots of them didn't believe it," he said.

"Lots of them wanted me to keep it quiet, some said 'Why don't you do a statement? Why don't you do a magazine cover? Why don't you do a TV interview?'.

"I didn't want to get my words twisted. I wanted to put an end to all the rumours and speculation.

"I'm still Tom. I still want to win an Olympic gold medal at Rio 2016 for Great Britain. I'm still as motivated as ever to do that."

He said the decision to reveal details of his relationship came after he was misquoted in an interview.

"It made me feel really angry and frustrated," Daley added.

"Emotions I've never felt before when reading something about myself. Honesty is something I really believe in and I've always been honest. I may have been vague in some of the answers but I've always been honest."

Daley has gained legions of young female fans since bursting on to the sports scene, representing Great Britain at the 2008 Beijing Olympics aged just 14.

He went on to win two golds at the Commonwealth Games in Delhi in 2010, before adding an Olympic bronze medal in the men's 10m platform event at London 2012.

Days after his Olympic medal win, thousands of supporters queued to meet their idol at book signings across the country, with some reportedly being turned away at a shopping centre near Bristol because the queue was so long.

Daley also hosts ITV entertainment show Splash! where celebrities are given the chance to test their diving skills, which is set to return for its second series next month.