A Belgian soldier at the departure hall of Brussels airport in Zaventem | John Thys/AFP via Getty Images Brussels Airport police detained 30 on suspicion of terrorism in one month Authorities stepped up counterterrorism measures after the March 2016 attacks.

More than 30 people were detained at Brussels Airport on suspicion of “links with terrorism or offenses linked to the security of the state” in the space of a month late year year, local media reported Monday.

The arrests were made by anti-terror police between mid-November and mid-December, according to the reports. Interior Minister Jan Jambon said it was “too early” to give exact details.

After the bombings at Brussels International Airport and Maalbeek metro station in March 2016, authorities stepped up counterterrorism measures. Some 109 specially trained officers have been deployed since the terror attacks, with most of them working at the airport. Others are part of the railway police unit, after it emerged that the terrorist who drove a lorry into a Berlin Christmas market in December had traveled through Brussels North train station.