• Border crossing between Germany and Switzerland at Rheinfelden reopens after explosives alert and vehicle inspection triggers evacuation and closure.
• Explosives detection dogs reacted to a car with German number plates, leading to evacuation of designated danger zone and closure of A861 highway.
• Two German nationals taken into custody following suspected security threat, but police confirm no hazardous substances found and motorway reopened.

A border crossing between Germany and Switzerland reopened late on Wednesday after shutting for several hours due to an explosives alert.

During a border check in the afternoon at the Rheinfelden crossing, explosives detection dogs reacted to a car with German number plates.

A designated danger zone was evacuated due to the suspected security threat, and special units from the Federal Police were called in.

The two occupants of the car, both German nationals, were taken into custody. By the evening, it was unclear whether they remained in custody.

The police did not confirm media reports suggesting that the men were father and son and that both had been the subject of a manhunt.

"No hazardous substances were found," said a police spokesman. "The motorway has been reopened."

The closure affected the A861. The motorway links the A98 on the German side with the Swiss A3, and is used by around 30,000 vehicles each day.

According to the German automobile club ADAC, there were traffic jams stretching for several kilometres on both sides.