LONDON, Feb 1 (Reuters) - Shipping disruptions in the Red Sea are negative for gross margins, Adidas CEO Bjorn Gulden said on Thursday in a call with analysts, adding that "exploding" freight rates are driving up costs and shipping delays are causing some delivery issues.

"Currently the spot rates are exploding again so if you don't have a long-term contract or you ship more than your contract there is an increased cost because of that," Gulden said.

"There is a delay currently of about 3 weeks which of course causes some delivery issues, especially to the European market," he added.

Shipping firms are avoiding the Suez Canal due to attacks on shipping in the Red Sea area and rerouting around the southern tip of Africa, delaying the arrival of clothes and shoes in Europe from factories in Asia. (Reporting by Helen Reid; editing by Jason Neely)