Russian President Vladimir Putin on Wednesday said Denmark as a "small country" faces pressure to block the controversial Nord Stream 2 gas pipeline but it will be built on another route if necessary.

The pipeline being constructed under the Baltic Sea by Russia's Gazprom energy giant is nearly complete but Denmark has not granted permission to cross its exclusive economic zone, which is outside its territorial waters.

"Denmark is a small country, it is coming under strong pressure," Putin said in televised comments at an energy forum in Moscow.

"It's up to (Denmark) whether it's able to demonstrate its independence and show it has sovereignty. If not, there are other routes," he added.

"It will be more expensive and will push us back a bit, but I think the project will be completed."

Gazprom chairman Viktor Zubkov said earlier Wednesday at the same forum that if Denmark refused permission, the pipeline could bypass that area of sea.

"If they don't approve it... we will go around Denmark's economic zone," he said, quoted by state news agency TASS.

The energy link will double the capacity to ship gas between Russia and Germany, sparking concerns about Western Europe's increasing dependence on Russian gas.

It has also raised fears that Moscow will be able to increase pressure on Ukraine, as Europe will be less reliant on the country for transiting supplies.

Its proponents -- led by Germany, the EU's biggest economy -- say the pipeline will provide reliable supplies at an acceptable price.

Putin made his comments at the Russian Energy Week forum in Moscow
Putin made his comments at the Russian Energy Week forum in Moscow Sputnik / Aleksey Nikolskyi

'Hostage to Russia'

US President Donald Trump however has threatened to hit Nord Stream 2 and those tied to it with sanctions, saying it makes Germany "a hostage to Russia."

"The US unfortunately has always been against our cooperation on energy with Europe," Putin said Wednesday.

Zubkov said the pipeline would provide "gas for Europe".

Gazprom said on Tuesday that the pipeline was 83-percent complete, with more than 2,000 kilometres (1,240 miles) laid.

"We have practically reached... Denmark's economic zone," Zubkov said, adding that if Copenhagen gave the green light, the project could be completed in "four to five weeks".

Russian Energy Minister Alexander Novak said he was still counting on Denmark granting approval.

"We don't see any basis not to give such a permit," he said.

Half of the 9.5-billion-euro ($10.6-billion) project is financed by Gazprom, with the rest covered by its European partners: Germany's Wintershall and Uniper, Anglo-Dutch Shell, France's Engie and Austria's OMV.

The project is threatened not only by possible US sanctions but by a change in EU law to unbundle the ownership of gas supplies and transportation networks. Gazprom both extracts and transports gas.

A transit agreement between Kiev and Moscow expires at the end of this year, prompting concerns over supplies to Europe this winter.

Putin said Russia was "ready to work within European legislation to sign an agreement on transit with Ukraine," as Kiev had recently decided to comply with EU gas market rules.