OAKLAND — A buildup of ships and cargo has led Port of Oakland terminal operators to begin hiring 400 new dockworkers, port officials said Thursday.

The first of the new hires are arriving this week and more will be brought in through September, port officials said in a news release.

Port operators intend to accelerate cargo operations and clear out a backlog of vessels anchored in the bay.

“We’re not operating with the speed and efficiency our customers deserve right now,” Maritime Director John Driscoll said in the release. “Additional longshore labor is an important first step in getting back on track.”

Port representatives said waterfront employers and the longshore union agreed last month to beef up Oakland’s labor pool.

In addition to adding workers, they agreed to train and promote 100 current workers. That will expand the workforce available to fill positions requiring greater skill and experience.

The hires are the result of a steady, three-month increase in container cargo over the same time last year, with some anchored “in the bay two days waiting for short-staffed terminals to clear vessels from berths,” according to the news release.

Also, port officials say, more auto carriers and cruise ships are coming into the bay, further straining the supply of dockworkers.

Cargo and vessel delays should ease by the end of July, the port administration said. It is discussing with waterfront labor and management other ways to accelerate cargo operations.

The port doesn’t hire longshore labor. That is managed by marine terminal operators who lease their facilities from the Port of Oakland.

Contact Andrew McGall at 925-945-4703. Follow him at twitter.com/AndrewMcGall.