Kenyan police are investigating the killing of an LGBTQ rights activist whose body was discovered stuffed in a metal trunk in a killing that has sparked national outrage.

Edwin Chiloba, a 25-year-old fashion designer and model, was found dead by the roadside Wednesday some 40 kilometres (25 miles) outside the Rift Valley town of Eldoret, media reports said.

Police spokesperson Resila Onyango told Kenya's The Star newspaper that the motive of the killing was still unknown.

"Experts are handling the matter," Onyango said.

Rights activists have called for speedy investigations into attacks on LGBTQ people who face a precarious existence in the predominantly conservative Christian nation.

Homosexuality is taboo in Kenya and across much of Africa, and gays often face discrimination or persecution.

Attempts to overturn British colonial-era laws banning homosexuality in Kenya have proven unsuccessful, and gay sex remains a punishable crime with penalties that include imprisonment of up to 14 years.

"It is truly worrisome that we continue to witness escalation in violence targeting LGBTQ+ Kenyans," the Kenya Human Rights Commission said in a statement on Friday.

"Everyday, the human rights of LGBTQ+ persons are being violated with little consequence for perpetrators," it added, urging the police "to conduct swift investigations and ensure the killers are apprehended and prosecuted".

The Kenya LGBTQ Feminist Forum in western Kenya where Chiloba lived, said he had used "fashion to deconstruct gender and advocate for the rights of the marginalised group".

"We want to know as a community as Kenyans, what happened to Edwin, why he was murdered and who dropped his body at the scene," the group's programmes director Becky Mududa said.

The death of Chiloba comes after another LGBTQ activist was found murdered in April last year.