Norway, now the biggest supplier of gas to Europe, will beef up security around its oil installations, it said following allegations of sabotage on Nord Stream's Baltic Sea pipelines. 

"The government has decided to put measures in place to increase security at infrastructure sites, land terminals and platforms on the Norwegian continental shelf," Norwegian Energy Minister Terje Aasland said in a statement late Tuesday.

The announcement came after three unexplained gas leaks, preceded by two explosions, occurred on the Nord Stream 1 and 2 pipelines on Monday, as well as recent drone observations reported by oil companies around their platforms in Norwegian waters.

European leaders have blamed the leaks on sabotage. 

After the drone observations, the Norwegian Petroleum Safety Authority earlier this week called for "increased vigilance from all operators and shipping companies on the continental shelf", noting that they could cause an accident or attack.

Concerns intensified after the spectacular gas leaks on Nord Stream's pipelines linking Russia to Germany under the Baltic Sea.

"Many things could suggest that it is an act of sabotage", Aasland said.

Norway has become Europe's main gas supplier in the wake of the war in Ukraine, taking the place of Russia. 

The Scandinavian country has a vast network of pipelines linking it to the continent, which experts have said are at risk of sabotage.