The United States and Japan ended the first day of round six of their official civil aviation talks Monday at the Transport Ministry by reconfirming their differences on key issues in the protracted dispute.

The two sides hope to hammer out a four-year transitional agreement on the air market. "The meeting started and ended with discussion of practical matters," a Transport Ministry official said. "We have started groping for possible compromises."

On Monday, negotiators in the three-day, vice-ministerial-level talks covered such issues as code-sharing, fare systems and business opportunities for the so-called nonincumbent carriers that currently operate under restricted conditions in the trans-Pacific market. The U.S. is demanding that Japan liberalize access to its smaller, regional airports. But Japan is fighting to keep the restrictions.

On the issue of beyond rights, where U.S. airlines fly to third countries via Japan and vice-versa, the two sides remain apart on such matters as the number of flights to be allowed, and calculating the proper ratio of Japan-bound to third-country-bound passengers.

On code-sharing, where two airlines team up to offer passengers more flexible routes, the U.S. and Japan are at odds over whether to allow such operations in the U.S.-Japan market to be carried out by two carriers based in the same nation. Also being debated is whether such carriers would be allowed to freely operate code-sharing on routes to third countries via Japan or the U.S. Japan is against code-sharing by same-nation carriers.