United Nations University in Tokyo is considering relocating its main research facility to Yokohama, possibly this spring, sources said Tuesday.

The move comes after the Tokyo Metropolitan Government, citing financial difficulties, demanded last year that the national government shoulder the estimated 860 million yen a year needed to host the university, prompting the U.N. body to discuss the matter with the foreign and education ministries.

Tokyo Gov. Shintaro Ishihara made the request in writing to the Foreign Ministry, saying the national government should shoulder the annual rent of about 730 million yen and some 130 million yen in operating costs, including electricity.

The university is the sole U.N. facility headquartered in Japan. Unlike conventional universities, it is an international academic research body.

The metropolitan government has lent the facility free of charge and paid other costs of the university's Institute of Advanced Studies, which is adjacent to the university headquarters in Shibuya Ward.