A police department in northwestern Germany has drawn criticism for sending a letter to refugee home administrators advising them against sending their Muslim residents to the Carnival celebrations because it could lead to “undesired interactions” with the general public, according to local reports Monday.

The report comes as several cities throughout the North Rhine-Westphalia region, which is the most populous Germany, are preparing to welcome millions of visitors to their Carnival celebrations later this February. Authorities in the region might have concerns about terrorist attacks happening at the Christian festivities that commemorate a period of fasting before Easter, because of the troubling history of Islamic militants targeting Western religious events.

A number of social rights groups last year organized excursions bringing refugees and Germans citizens to Carnival events together to educate the newcomers about the religious celebrations.

In addition to telling the housing administrators not to organize trips for their residents to attend the festivities, the letter also implored the refugees living there to “undergo police searches without complaint.”

A representative of one of the refugee centers that received the letter, Petra Jennen, told local reporters, “I won’t be telling the families we have living here that they can’t go to the Carnival parade.” She added that asking the refugees to endure additional screening procedures was “very unfair” because the police department would never ask such a thing from a German citizen.

Germany admitted 1.14 million foreign immigrants into the country in 2015, which was the largest amount in its history. Conservative pundits in Germany blamed the country’s seemingly lenient migration policy for the Christmas attack in Berlin where a Tunisian national killed 12 people by driving a truck into a crowded area. The anti-migrant sentiment might have played a significant role in the more than 3,000 crimes committed against refugees in Germany in 2016, according to a report from the country’s Federal Criminal Police Office Friday.

Marion Heuser, a spokesperson for Germany’s left-leaning Green Party, defended her party’s stance on immigration while expressing dismay over the North Rhine-Westphalia's police letter.

“Many people have committed themselves to helping people stranded here better understand Germany's sometimes strange culture. Carnival should be understood as a colorful and mixed celebration. And now refugees should be kept away from it?” Heuser wrote on Facebook.