But the opposition Social Democratic Party (SPD) has called for an explanation, with Thomas Oppermann, chief SPD whip, saying the minister must explain "how he plans to overcome the damage that has arisen".
Niebel stressed the procedure to pay the custom duty was now in hand. "I regret that the claim for payment of duty was only done with a delay," he said to Spiegel Online.
"Obviously I always comply with all my legal duties in my professional and private business," he added.
Source: AFP