Denmark on Monday warned its citizens not to travel to Saudi Arabia amid growing tensions between Arab and Nordic countries over cartoons of the prophet Muhammad that have offended Muslims.

The row, sparked by cartoons published in the Jyllands-Posten newspaper last September, could also turn into an international trade dispute following a warning from Peter Mandelson, the European Union’s trade commissioner, that the EU would take Saudi Arabia before the World Trade Organisation if the Saudi government encouraged a boycott of Danish products, which started last week.