The US military and intelligence community are becoming concerned that Russia could cut underwater cables during a diplomatic crisis, bringing the internet grinding to a halt.

The New York Times reported that US spies had noticed Russian submarines and spy ships acting suspiciously near cables in the North Sea, north-east Asia and off the American coast.

The paper said more than 12 officials had confirmed the issue was attracting considerable interest in the US Department of Defence.

About £6.5 trillion-worth of business deals are transacted across underwater cables every day. Officials added that the Russians could also be looking for secret military cables used by the US.

Commander William Marks, a US Navy spokesman, said: “It would be a concern to hear any country was tampering with communication cables. However, due to the classified nature of submarine operations, we do not discuss specifics.”

Rear Admiral Frederick Roegge, commander of the US Navy’s Pacific submarine fleet, said: “I’m worried every day about what the Russians may be doing.”

The US Navy has a submarine, named after former President Jimmy Carter, which is believed to be capable of listening into the communications passing through underwater cables.

Cutting the cables, however, would potentially cause economic chaos due to the dependence of the West, in particular, on the internet.

Michael Sechrist, a researcher who has studied the security of undersea cables, said: “The risk here is that any country could cause damage to the system and do it in a way that is completely covert, without having a warship with a cable-cutting equipment right in the area.