Pro-Kurdish demonstrators staged protests against Turkey’s military offensive in northern Syria on Sunday, scuffling with Turks and German police at Duesseldorf airport, while in Britain they temporarily closed two train stations, authorities said.

Several people in Germany were left injured after police used pepper spray against some demonstrators opposed to Turkey’s ongoing military operation Olive Branch against the Kurdish People’s Protection Units (YPG) in Syria’s Afrin region.

The unannounced rally of about 150 people – one of several Kurdish demonstrations in Germany at the weekend – turned rowdy and led to “a number of people suffering injuries”, federal police said.

Images on social media showed the protesters holding a banner that read "Afrin is becoming our Vietnam – we will defeat fascism".

Turkish President Recep Tayyip Erdogan has threatened to “purge” Kurdish militia from the town of Afrin as his forces and allied Syrian rebels advanced to within a few kilometres.

In Britain on Sunday, flag-waving pro-Kurdish protesters forced the closure of Manchester Piccadilly train station and King’s Cross station in London.

In the capital, British police massed at the station entrance to prevent the crowd marching onto the concourse or platforms, causing service interruptions.

Meanwhile in Manchester, scores of demonstrators made it onto the tracks, closing the station for several hours, which led to trains being halted and impacted travellers across the country.

Superintendent Mark Cleland of the British Transport Police said: “Those involved in this afternoon’s incident will be subject to intense investigation with a view to arrest and prosecution.”