Police in Strasbourg Monday used tear gas and water cannons to disperse thousands of dockers who marched to the European Parliament to protest against plans to liberalize port services, the BBC reported.

An estimated 6,000 protesters joined the rally with at least 13 dockers arrested and 12 policemen injured in violent skirmishes.

The dockers were protesting against the European Union's Port Package II program, which aims to end monopolies on cargo handling by terminal companies, and to permit shipping firms to appoint independent contractors to load and unload vessels.

Elsewhere in Europe, striking dockworkers effectively closed down the continent's largest ports, Rotterdam in the Netherlands, Antwerp in Belgium and Le Havre in France. Greek, Danish, Swedish and Portuguese dockers also went on strike, while dockers in the United Kingdom, Italy and Poland continued operations but sent delegations to the rally in Strasbourg.

The EU's Port Package II proposals will be debated in Strasbourg Tuesday, with a vote expected Wednesday. The European Parliament rejected a similar bill three years ago, and the same result is expected this week, the BBC said.