WASHINGTON (AP) _ The United States and Japan reached agreement on a new ``all-cargo'' air services arrangement to provide new opportunities to air carriers from both nations, the White House said today.

A White House announcement said the arrangement, expected to be formally concluded in mid-April, ``builds upon existing treaty rights for U.S. and Japanese carriers.''

``The United States has consistently indicated its determination to expand opportunities for Japanese and American carriers,'' the announcement said. ``It has also consistently indicated that existing rights must be respected.''

Daniel Turullo, assistant secretary of state for economic and business activities, told reporters the agreement will improve conditions for major U.S. air cargo carriers already serving Japan. It also will give the United States the right to designate an additional carrier in what Turullo said is a growing $10 billion a year market.

Japanese air cargo carriers also will get expanded rights to operate to and from the United States, he said.

``What this means in practical terms is more flying by cargo carriers on both sides,'' he said.

Presently, U.S. cargo service to Japan is handled primarily by Federal Express, Northwestern and United Airlines, with United Parcel Service enjoying only limited rights.

Turullo said rights for all four carriers will be expanded under terms of the agreement.