Russia's ambassador to Denmark said Saturday that the NATO country's navy could be targeted by nuclear missiles if it joins the Western alliance's anti-missile shield.

The threat made by Ambassador Mikhail Vanin in an opinion piece he wrote for the Danish daily Jyllands-Posten sparked an angry reaction and came amid an increasingly Cold War-style standoff between Moscow and the West.

"I do not think that the Danes fully understand the consequences of what happens if Denmark joins the US-led missile defence," Ambassador Mikhail Vanin wrote in the daily.

"If this happens Danish warships become targets for Russian nuclear missiles."

Russia has long opposed NATO's missile shield -- launched in 2010 and due to be fully operational by 2025 -- in which member countries contribute radar and weaponry to protect Europe against missile attacks.

Denmark has pledged to supply one or more frigates equipped with advanced radar to track incoming missiles.

The chairwoman of the Danish parliament's foreign affairs, Mette Gjerskov told AFP that the comments were "very threatening and not necessary" as the missile shield was simply an "intruder alarm" and no danger to Russia.

"This is a way of escalating the verbal tone between Russia and NATO," she said, adding that the comments were also aimed at Russian public opinion.

"But it doesn't change the fact that we're not afraid."

Denmark's Foreign Minister Martin Lidegaard said the remarks were "unacceptable rhetoric" and "completely out of proportion".

"One should not threaten such serious things as the ambassador has done here," he told news agency Ritzau.

Tensions between Russia and the Nordic countries have risen in recent years with reports of increased Russian airforce incursions in the Baltic region.

Holger K. Nielsen, defence spokesman for the Socialist People's Party, which is opposed to Denmark's involvement in the NATO shield, called the ambassador's comments "crazy".

"His opinion is based on the assumption that a war has broken out and in that case Denmark, as a member of NATO, would already be a target," he told Jyllands-Posten.

NATO's European missile defence system is headquartered in Ramstein Germany since 2012.

It includes US missile destroying warships in Spain, Patriot anti-missile systems in Turkey, ship borne radar systems carried by several member countries and planned missile interceptors in Romania.