Slovenia said Saturday it temporarily suspended beefed-up checks on the EU's external border hours after the new regulation -- aimed at stopping suspected Islamist fighters returning from Iraq and Syria -- came into force.
Hundreds of cars and buses had found themselves stuck on Slovenia's border with Croatia on Friday after the implementation of the new regulation.
Bojan Tomc, a police spokesman from Novo Mesto, near the Obrezje border crossing with Croatia, told state television that since 10 pm (2000 GMT) on Friday police had "suspended checks of EU citizens and continued checking only those from third countries".
Bostjan Sefic, state secretary at Slovenia's Interior Ministry, told the broadcaster that the tougher checks were relaxed at "some border crossings" in accordance with the rules but did not give further details.
Slovenia controls 670 kilometres (420 miles) of the EU's external border with Croatia and was a key transit country along the so-called Balkan migrant trail until the route was shut in March last year.
The EU said Thursday the systematic checks at the bloc's Schengen borders were designed to tackle "foreign fighters" returning from Iraq and Syria.