A nationwide strike by construction workers in Panama on Tuesday stalled already delayed work on expanding the Panama Canal, a union leader said.

"The strike is successful across all the country. More than 90 percent of worksites are paralyzed, among them the Panama Canal expansion," Saul Mendez, secretary general of the SUNTRACS union told AFP.

The union, the biggest in the country, called the stoppage to protest "corruption in the courts" and a possible hike in retirement age.

It was the latest in a number of strikes over the past few months that SUNTRACS has organized to press demands on the government.

Although the Panama Canal was not the main target of the latest strike, it exacerbates delays that have already pushed back work well beyond an original October 2014 deadline. The consortium responsible for the project is now aiming for an April 2016 end date.

The work on the century-old canal has been going on since 2007 with the aim of tripling its capacity.

The cost of the work was projected at $5.3 billion, but that has been greatly overrun as well, leading to disputes between the Spanish-led consortium and the state Panama Canal Authority.