Ride-hailing app Uber said it is joining a global public transport association to improve mobility in the cities it operates in, although North America's largest public transit union said there was no place for the U.S. company.

Uber's move to join the International Association of Public Transportation (UITP) is part of a drive by Uber to improve its relationships with local authorities after a series of regulatory and legal setbacks.

UITP represents public transport providers around the world, including Transport for London (TfL) — which in September stripped Uber of its operating license.