Russian Vessels Photographed at Nord Stream Site Days Before Blast

Denmark’s military said it photographed a number of Russian vessels near the blast site of the Nord Stream pipeline sabotage days before the explosions took place.

Russian maritime activity isn’t unusual in the Baltic Sea, where the explosions that took the natural-gas pipelines out of commission last year. A senior European official familiar with the investigation into the explosions said the movements of the Russian vessels have long been known to investigators and have been dismissed as unlikely to be connected with the attack.

Four days earlier, on Sept. 22, a Danish naval patrol vessel, P524 Nymfen, took 112 photographs of several Russian vessels near the blast site, the Danish Defence Command said in a response to a freedom of information request from The Wall Street Journal.

The command declined to release the photographs because of what it said was their intelligence value. It added, following another freedom of information request, that 26 of the photographs were of a Russian vessel designated as SS-750, which can be equipped with a small submarine.

The existence of the 112 photographs was earlier reported by Information, a Danish daily.

Following the pipeline sabotage, initial suspicions in many European capitals focused on Russia, which denied any involvement. U.S. officials are investigating the possibility that a pro-Ukrainian group was responsible for the attack, the Journal previously reported.

Gas leaked into the Baltic Sea in September after explosions tore apart the Nord Stream pipeline. PHOTO: SWEDISH COAST GUARD/ASSOCIATED PRESS

Investigators in Germany have focused on the possible role of a sailing yacht called Andromeda and its six passengers, some of whom had Ukrainian passports, according to German officials briefed on the probe.

Some analysts have expressed skepticism that a sailing yacht could have played a key role in such an act of sabotage—involving several explosions at an underwater depth of 260 feet. The photos of the Russian ship have provided fuel for alternative theories.

The chance that the Russian vessel captured in the photo was near the blast site without being involved in the explosion four days later, “is infinitely small,” said Jens Wenzel Kristoffersen, a commander at the Danish navy and an analyst at the University of Copenhagen.

“I don’t have a smoking gun,” he said. “But in my opinion, there is no doubt as to who was behind it.”

Russia’s foreign ministry said Wednesday that allegations that it was involved in the Nord Stream sabotage were “part of the Western misinformation campaign to ensure that those who ordered and perpetrated this act of international terrorism are never identified.” 

Four Nordic public broadcasters have reported that at least three Russian ships able to perform underwater operations were present near the blast sites between June and September last year. 

The ships included the Russian naval research vessel Sibiriakov, the tugboat SB-123 and a third, unidentified vessel, according to the Danish Broadcasting Corporation. The vessels sailed with their position transmitters turned off, but their movements were tracked using intercepted radio communications sent to Russian naval bases.

Write to Sune Engel Rasmussen at sune.rasmussen@wsj.com