The European Commission is seeking clarification from Poland amid reports that Polish officials have been involved in a cash-for-visa scandal, according to a CNN report.

The Ministry of Foreign Affairs of Poland and Polish consulates have been accused of participating in an extensive illegal network through which Polish visas were granted to immigrants from Africa and Asia in exchange for large sums of money.

As Poland is a member of the passport-free Schengen area, visas issued by the country give holders free access to 27 member states of the Schengen areawhich includes 23 EU member states as well as Switzerland, Iceland, Norway and Liechtenstein and also allows entry to some non-Schengen countries.

The claims could further intensify a standoff in Europe over grain supplies, which has led to the suspension of arms shipments to Ukraine by Poland and to lawsuits by Kiev against three EU member states, including Poland.

Brussels is “watching very closely recent media coverage of these alleged cases of fraud and corruption,” according to European Commission spokeswoman Anitta Hipper.

“These allegations are very worrying and raise questions about compliance with EU law,” Hipper said in a statement on Wednesday. That is why Commissioner (Ylva) Johansson has written to the Polish authorities to ask for clarification.”