“Anyone entering Germany must expect to be checked. Federal and state police are working hand in hand here,” Seehofer told Bild am Sonntag newspaper.
A new rule requiring everyone returning from abroad to be able to present a negative coronavirus test at the border came into force on Sunday.
The rule applies for everyone over the age of twelve who is not fully vaccinated against the virus or who has not recovered in the past six months.
Previously only people arriving at airports were expected to provide a negative test result. The new regulation extends it to rail and road entries. Exceptions apply to commuters.
The interior minister said that border police would conduct spot tests at land borders in order to minimize traffic jams at a time when many Germans are returning from summer vacations abroad.
With school holidays ending in three northern states this Sunday, traffic jams tens of kilometres long were already reported at some border crossings last week, a situation that the spot checks could exacerbate.
“When entering from countries outside the EU, at airports and seaports, everyone will be checked, without exception,” Seehofer said.
Those who don’t have a negative test may have to go into quarantine and could face “hefty fines”, he warned.