Children of Pennsylvania daycare centre admitted to hospital after Carbon Monoxide leak incident

The Nord Stream 1 and 2 pipelines, connecting Russia and Germany, saw unexplained gas leaks earlier this week.

Both Denmark and Germany have raised concerns that the leaks are the result of a sabotage attempt, leading to investigations being launched.

Denmark's armed forces released a video showing bubbles rushing to the surface of the Baltic Sea above the pipelines, and said the largest gas leak had caused surface disturbance of well over 1 kilometre in diamete

The operator of the Nord Stream 2 gas pipeline reported a sudden drop in pressure overnight on Monday, followed by the Danish authorities spotting a leak around pipelines lying in Danish waters.

Made up of 100,000 24-tonne concrete-weight coated steel pipes laid on the seabed, the Nord Stream pipelines are placed at a depth of 80-110 metres.

Analysts and experts say such leaks are very rare and Nord Stream AG has called leaks on three strings of the offshore gas pipelines "unprecedented," according to Reuters.

Possible causes range from technical malfunctions, a lack of maintenance or even possibly sabotage.

Russia said it did not rule out sabotage as a reason behind the damage, adding it was an issue affecting the energy security of the "entire continent," while Poland backed up the stance and Denmark said it can’t be discounted.

Gas leaking from the damaged pipelines could ignite over the water, as well as causing vessels to lose buoyancy. The largest leak has caused surface disturbances of well over 1 kilometre in diameter.