Japan will request that a joint panel with the United States be convened at an early date to probe last week's crash of a U.S. Marine Corps helicopter on a university campus in Ginowan, Okinawa Prefecture, Japanese officials said Wednesday.

The move comes after the U.S. military on Tuesday upheld its right to reject a request by Japanese police to conduct an on-site investigation into the crash of the CH-53D helicopter, and amid growing calls for Japanese involvement in the accident probe.

Also Wednesday, Ginowan Mayor Yoichi Iha handed a letter to the Foreign Ministry, seeking more details on the crash and pressing for the return to Japan of the U.S. Marine Corps Futenma Air Station site. Japan and the U.S. in 1996 agreed on the base's return, pending construction of a replacement site in Okinawa.

Japan decided to call for the panel -- a subcommittee of the Japan-U.S. Joint Committee -- to convene a meeting in light of the seriousness of the crash, the officials said. The committee oversees implementation of the Japan-U.S. security treaty.

The subcommittee, if formed, would consist of U.S. military representatives in Japan and officials from the Foreign Ministry and the Defense Agency. It would be tasked with compiling a report on the cause of the crash and report to the Joint Committee.

The subcommittee last convened in 1997 to look into a U.S. military plane crash in Yokohama.