German authorities fear the possibility of a new migrant route forming after discovering 51 migrants hiding in a truck near the Polish border in Brandenburg.

Brandenburg police discovered the migrants, 17 of which were children, after stopping the 46-year-old Turkish driver on the A12 motorway on Saturday evening. Police say that most of the migrants found in the truck came from Iraq and that most were already registered as asylum seekers in Romania and Bulgaria in late August and early September, Die Welt reports.

The German federal police are now investigating the incident along with several other migrant incidents that have occurred in recent weeks along the Polish border.

Only a few days before the discovery of the migrants, police in the town of Bad Muskau in Saxony took 40 Iraqis into custody. They claimed that the Iraqis had been smuggled in a truck through Poland and then dropped off where they then walked across the border into Germany.

In late August, federal police found 20 Iraqis and Iranians, including children, in Brandenburg who has been smuggled into Germany in a similar way.

Of the 51 migrants, only one, a 23-year-old Syrian, had any form of documentation. According to investigations and testimony from the man, some of which police said was contradictory, the migrants were trapped in the truck for two days and were not let out.

A judge has ordered warrants for the arrest of both the truck driver and any possible accomplices on charges of human trafficking.

The Polish border has largely been limited to Chechen migrants in recent years as many Middle Eastern migrants have used the Balkan route or the Mediterranean route to get to Western Europe.

Now that the two main routes have largely closed, people smugglers have turned to other options like Spain which has seen a dramatic rise in the number of migrants since last year.

Last month, migrants were caught on camera storming a Spanish beach as tourists and locals looked on as the migrants disappeared before police could arrive.

Romania has also seen an influx of migrants as people smugglers have used boats to transport people across the Black Sea from Turkey. Earlier this month, the Romanian coastguard picked up 87 migrants in a single operation.