Germany began random checks on Monday at its borders with five western European countries as it seeks to crack down on irregular migration, kicking off a system of checks already in place at four other borders.
Police checks have begun at the borders with France, the Netherlands, Belgium, Luxembourg and Denmark and will continue for the next six months. Germany has already been maintaining border controls with Poland, the Czech Republic, Austria and Switzerland since last year, AP reports.
Germany, a member of the European Union, said last week it would expand border controls at nine land borders in an effort to stop irregular migration and crime following recent extremist attacks.
Border controls are testing European harmony, as some see it as a departure from the EU's free travel arrangement known as Schengen. The freedom of European citizens to travel freely across borders for work or pleasure is one of the most cherished benefits of the EU.
According to the EU, member states are allowed to temporarily reintroduce controls at the EU's so-called internal borders in the event of a serious threat, such as internal security. It is also stated that controls should be implemented as a last resort in exceptional situations and should be limited in time.
Such restrictions are often imposed during sporting events, including the Paris Olympics and the European football championship.
German Chancellor Olaf Scholz's coalition government has imposed border controls as it tries to crack down on irregular immigration, after the far-right won big in the last two state elections in eastern Germany. Another election will be held next Sunday in Brandenburg, the state surrounding Berlin.