Water has begun flooding into an expanded section of the Panama Canal as engineers begin testing new locks. It's a key step in a project that will affect trade across the world.

Officials overseeing the multibillion-dollar canal expansion project say they began testing new locks on the Atlantic coast Thursday.

Workers will spend the next several months filling locks on the Atlantic and later the Pacific with water from an artificial lake.

The expansion that started in 2006 will allow the canal to accommodate vessels capable of carrying 2.5 times the number of containers held by ships currently using the canal.

Work on the project is 90 percent complete. Officials expect the expanded canal to open by April 2016.