The pilots who have to lead ships into the two ports demand that their profession be exempted from the government plans to add two years to the retirement age.
Some sixty ships were blocked by the all-night strike and go-slow actions on Monday and Tuesday. Antwerp, one of the biggest ports in the world said it was costing about €1 million (€1.3 million) every hour.
The government is expected to announce the full pension plans later Tuesday.