Another alliance of major shipping lines has raised the concerns of the Federal Maritime Commission, which wants more information on its impact.

The G6 Alliance Agreement among six major ocean carriers last month filed plans to extend their cooperation to all major trade routes between Asia and the US west coast, and between Europe, the Mediterranean and the US Gulf and east coasts.

The expanded cooperation agreement also calls for the operation of 180-220 ships with a maximum capacity of 14,000 twenty foot equivalent units (TEU), and operating one or more service centres.

The G6 Alliance includes American President Lines, Hapag Lloyd, Hyundai Merchant Marine Company, Mitsui OSK Lines, Nippon Yusen Kaisha, and Orient Overseas Container Line (OOCL).

"It is imperative the Commission fully understands the implications of what has been proposed," said Commissioner Richard Lidinsky Jr.

"Of particular concern is how the proposed service centres will operate autonomously of the parties to the agreement, and how the five members of the alliance belonging to the Transpacific Stabilization Agreement (TSA) will act independently from the one lone independent carrier in setting rates for certain routes covered by the agreement."

The G6 Alliance follows on the heels of plans by three of the world's largest container carriers to establish an operational alliance on east-west trade.

Maersk Line, CMA-CGM, and Mediterranean Shipping have teamed up as the P3 Network and say they will begin cooperating in the second quarter of 2014 on routes covering Asia to Europe as well as transpacific and transatlantic routes to the US.

Early estimates by Maersk Line put market control of such an alliance at about 42% on the Asia to Europe route, 24% on the transpacific routes, and 40-42% on the transatlantic route.