Striking dock workers in Rotterdam have clashed with police during a protest over European Union plans to liberalize port services.

Netherlands police are reporting several arrests after a group of demonstrators threw stones and other objects at the officers.

More than 7,000 dock workers stopped work and halted traffic Monday in Rotterdam, Europe's largest port.

Workers from other ports across Western Europe joined the protest.

The dock workers are concerned about job security, safety issues and EU plans to allow port authorities to choose whom they hire. They argue that job safety will suffer if port authorities are allowed to import laborers from other European countries where workers are willing to work for lower wages.