A remotely operated mini submarine was being flown to the site and would likely be deployed in the early hours of Friday to help verify whether a discovery had been made, he added.
A search for survivors would continue, the rescue center said, noting that the helicopter was equipped with life rafts.
Russia’s Emergency Ministry said the five crew and three passengers were Russians. The Russian-made Mil Mi-8 aircraft had been reported missing around 1335 GMT.
The three passengers were working for Russia’s Arctic and Antarctic Research Institute, the Russian Energy Ministry said in a statement.
The helicopter was on its way from the abandoned Pyramiden settlement to the coal mining port of Barentsburg, but was later confirmed to have gone down in the ocean a few kilometers from its destination.
Several vessels were in the area, according to shipping data from Marinetraffic.com. The ship of the governor of Svalbard, the Polarsyssel, was coordinating the search.
The Russian coal company Arktikugol runs the coal mine at Barentsburg, which employs Russian and Ukrainian miners.
An official at the Russian company Convers Avia Air told Reuters it owned the helicopter and had lost communication with it.
Earlier, Hongset told Norwegian broadcaster TV2: “For every minute that goes by, the risk of hypothermia and death rises.”
Located around 700 kilometers (435 miles) north of the European mainland, Svalbard is governed under a treaty that grants NATO-member Norway sovereignty while allowing other signatories to do business and exploit natural resources.
More than 40 countries are parties to the treaty. Moscow has maintained a presence on the islands for decades as a strategic foothold in the high north.
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