PANAMA CITY – Work to expand the Panama Canal — interrupted earlier this year for a dispute over cost overruns — halted Wednesday, this time for a strike by workers demanding higher wages.

“The project to enlarge the Panama Canal … is paralyzed,” said Saúl Méndez, secretary general of the construction-worker union Suntracs.

Work had halted for 15 days in February in a row over who would pay for an estimated $1.6 billion in cost overruns in the multi-billion-dollar project to build extra locks on the 80-kilometer (50-mile) waterway linking the Atlantic and Pacific Oceans.

The project was already running late, and is now estimated to be up to a year behind schedule. It had originally been due to be completed next year.

Now the union is demanding wage increases of 20 percent, which the employers have said is excessive.

Grupo Unidos por el Canal (GUPC), the consortium running the expansion project, said that Suntracs workers “are heeding the call to strike,” which “is impacting the work schedule of this project.”

The canal, completed by U.S. interests in 1914 to create a shortcut and safer journey for maritime traffic, is used by 13,000 to 14,000 ships each year.

The expansion — one of the biggest civil engineering operations in the world — will add a third set of locks to the canal.