The International Transport Workers' Federation and the Panama Canal Authority (ACP) are in a brewing tiff related to the work schedules and staffing on the Canal's tugboats.

The ACP says it disciplined several tugboat captains for taking part in an April work stoppage for operations on the larger locks on the Canal. Neo-panamax ships transiting the Canal require two tugs to escort them through the locks.

Transits faced a brief interruption, but they soon resumed normal operations, the ACP said.

The tugboat captains were protesting the ACP's decision to reduce the amount of seamen on a tug, in addition to the master and engineer, from three to two.

The ACP contends that the reduction in the number of seamen is in-line with the long-term plan for operations on the neo-panamax locks. It's doing so after having seen over 3,000 transits on the neo-panamax locks.

The ITF, though, is advocating on behalf of the tugboat captains, saying the disciplinary move was retaliation against the captains for bringing up safety issues on tugboat escorts through the Canal.

"The captains . . . must be able to ensure they can work in a safe environment for the prosperity of the Panama Canal," the ITF said in a statement.

The ITF cited a report a report from the US National Transportation Safety Board that faulted fatigue on the part of a Panama Canal tugboat captain for a collision last year between a tug and a US Coast Guard cutter.

The union says it is urging the ACP "to engage in constructive dialogue with Panama maritime unions to demonstrate a serious consideration for safety in one of the shipping industry’s most crucial waterways."