A German shipping firm on Monday dismissed reports one of its vessels was carrying Iranian arms bound for Syria in violation of EU sanctions against the regime of President Bashar al-Assad.

Respected news weekly Der Spiegel reported at the weekend that the ship, the Atlantic Cruiser, owned by German firm Bockstiegel but chartered by a Ukrainian firm, had been stopped on the high seas with Iranian weapons on board.

But Bockstiegel said: "According to the description of the goods in our documents as well as their appearance, the firm has no indication that they are weapons, ammunition or heavy military equipment, as stated in the press."

"The firm is in constant contact with the company that chartered the ship, which for its part stresses that the shipment for Syria did not contain weapons or military equipment, but exclusively legal goods for civilian use," it added.

The containers currently on the Atlantic Cruiser were loaded in the Indian port of Mumbai, Bockstiegel said. According to the shipping firm's documents, the equipment bound for Syria consisted of parts for a thermal power station.

Nevertheless, the firm acknowledged that "the crew only has access to the container stacked at the top". This was being inspected and appeared to consist of wires and cables, the statement said.

The firm has ordered the ship not to continue its journey until the facts are established and has agreed with the German government that the vessel would not dock in Syria until the cargo could be checked at a safe third-country port.

Bockstiegel did not say where this could take place, nor did it indicate the current co-ordinates of the vessel.

Quizzed at a regular news conference earlier Monday, a spokeswoman for Economy Minister Philipp Roesler stressed the legal difficulties of such a case, given the ship was flagged under a third country, Antigua and Barbuda.

Iran is under a UN arms embargo imposed in 2007 due to its alleged nuclear activities while Western countries have declared a similar embargo against Iranian ally Syria since a bloody crackdown on dissent began over a year ago.

"The shipping firm emphasises ... that it scrupulously respects existing laws. This of course also goes for the arms embargo imposed on Syria by the European Union," said Bockstiegel.