Selena Gomez celebrated her birthday with the launch of a campaign to make mental health services more accessible to under-served communities.

The American singer, who turned 28 on Wednesday, is known to be a mental health advocate and has spoken publicly about being diagnosed with bipolar disorder.

On Wednesday, Rare Beauty, the cosmetics line she founded earlier this year, launched the Rare Impact Fund, which aims to raise US$100 million (S$138 million) in 10 years, to increase the access of under-served communities to mental health services.

In an Instagram post, the company said it would be working towards the goal from its "very first sale" and that 1 per cent of its sales will go directly to the fund.

Mr Scott Friedman, chief executive officer of Rare Beauty, said: "With the launch of the Rare Impact Fund, we will create one of the largest philanthropic efforts focused on mental health in the world."

The company has also established the Rare Beauty Mental Health Council, which is made up of mental health experts, who will help to steer the company's efforts.

Gomez founded Rare Beauty in February this year and said earlier that its products will be launched in North America in summer.

The Lose You To Love Me singer does not shy away from discussions on her mental health. In April this year, she spoke with singer Miley Cyrus on her bipolar disorder in the latter's Bright Minded Instagram Live series.

On her recovery at McLean Hospital in Massachusetts, Gomez said: "Recently, I went to one of the best mental hospitals in... the United States, McClean Hospital, and I discussed that after years of going through a lot of different things, I realised that I was bipolar. And so, when I got to know more information, it helped me. It doesn't scare me once I know it."

Last year, the singer won the McClean Award given out by the hospital to individuals who have helped deepen the public's understanding of psychiatric illness and mental health.

In a statement, Gomez said: "Since the brand's inception, we wanted to find a way to give back to our community and further support people who needed access to mental health services, which have had a profound impact on my life."