The vessels, the four-masted Sedov and Kruzenshtern, "have been given instructions from home... we have no idea what's going on," Per Langhelle, chairman of one of Norway's tall ships, Statsraad Lehmkuhl, told the web site for newspaper Bergens Tidende.

Langhelle said the Russian ships' agent was "heartbroken," and that he'd talked to other Russians involved in the race. "They don't understand the order," he said.

Nor does the University of Murmansk, which technically owns the Sedov. "Because of reasons unknown to us, the Russian foreign ministry has decided that Russian ships won't be allowed to call at harbours in Britain, Ireland or Norway," reads a statement from the university.

Speculation has linked the port ban to everything from strained relations between Britain and Russia, to Russian fears the vessels might be seized while in port as collateral for unpaid debts.

Officials at the Russian Embassy in Oslo wouldn't comment, nor would Norway's foreign ministry, which was unfamiliar with the ban.

The Sedov, long a participant in the annual Tall Ships’ Race, had been expected to call at Måløy on August 1 and in Bergen on August 9.

The Sedov, built in 1921 in Kiel, Germany, was originally built as a cargo ship and long was the largest of its kind in operation. It was handed over to Russia along with the Kruzenshtern (built 1926) as war reparations in 1945 and today is used as a training vessel for cadets from the universities of Murmansk, Saint Petersburg and Arkhangelsk.