Gunmen riding on a motorcycle have shot and killed a transgender woman and her friend in Pakistan's northwestern city of Peshawar, police say.

The two were targeted as they traveled in a rickshaw late on March 27 and the motive for the killing was unknown, police officer Mohammad Tahir said.

Dozens of transgender people have been killed in recent years, mainly in the conservative Khyber Pakhtunkhwa Province, of which Peshawar is the capital.

The Trans Action Alliance, a local rights group, says 55 have been killed there over the past three years.

No one has claimed the killings, but Islamic extremists who associate transgender people with prostitution are active in the region.

Based on reporting by AP and Dawn