Hundreds of masked anti-immigration protesters have blocked roads leading to Britain’s busiest ferry port, clogging traffic and disrupting travelers and cargo vehicles heading for France. Police said Saturday they were “engaging with the protesters,” and roads reopened by midday. Social media footage showed dozens of men dressed in black standing across a major road near the port and shouting “stop the boats.” Dover has been the site of previous anti-immigrant protests focused on migrants crossing the Channel from France in small boats. The Labour Party government said the right to peaceful protest is fundamental to democracy but condemned the disruption.