The UN Human Rights Council has appointed its first independent investigator to help protect homosexual and transgender people worldwide from violence and discrimination.

The United Nations expert Vitit Muntarbhorn will have a three-year mandate to investigate abuses against lesbian, gay, bisexual, transgender and intersex (LGBTI) people.

Muntarbhorn is an international law professor at the Chulalongkorn University in Bangkok, Thailand, and has served on several UN bodies, including inquiries on Syria and as a special rapporteur on North Korea.

The UN agreed on the new role in June, after the 47-member council overcame strong objections by Saudi Arabia and other Muslim countries to adopt a Western- backed resolution by a vote of 23 states in favour and 18 against with six abstentions.

Human Rights Watch welcomed Friday's appointment, saying the UN council "made history".

The International Lesbian, Gay, Bisexual, Trans and Intersex Association (ILGA) said the newly created role was critical to give justice to LGBTI people who have been attacked, abused or discriminated against.

Hundreds of LGBTI people have been killed and thousands injured in recent years, in violence that included knife attacks, anal rape and genital mutilation, as well as stoning and dismemberment, the UN said in a report last year.

More than 2000 transgender and gender diverse people were murdered in 65 countries between 2008 and 2015, according to The Trans Murder Monitoring project, which is coordinated by LGBT rights group Transgender Europe.

In 2011, the UN rights body declared there should be no discrimination or violence against people based on their sexual orientation.