"The Russian Embassy views the step of the Estonian side as an open act of unfriendliness, which undermines Russian-Estonian relations and may have the most negative impact on the prospect for a mutually respectful dialogue and the spirit of neighborliness, to which the leadership of the Russian Federation has expressed support on repeated occasions," it stands in a statement made by the Russian Embassy in Tallinn on Wednesday.

According to the embassy, Zatulin was scheduled to arrive in Estonia on Thursday, March 29 to meet with Russian compatriots in Tallinn and Narva.

"As is known, he was elected to the State Duma in 2016 with the votes of Russian citizens living in Northeastern Estonia, among others," the embassy noted. "Meeting with voters is a direct duty of a deputy and this is what Zatulin intended to do."

A spokesperson for Estonia's Ministry of the Interior confirmed that Zatulin has been forbidden from coming to Estonia, adding that decisions like this are not commented on.

There was no immediate word on how the prohibition on entry was communicated to the Russian MP.

Zatulin is first deputy chairman of the State Duma Committee for CIS Affairs, Eurasian Integration and Relations with Compatriots. He is also the head of the Russian Institute of Diaspora and Integration and a member of the Foreign Policy Council and the Defence Policy Council of Russia.

Accusing Zatulin of inciting inter-ethnic hatred and undermining the territorial integrity of Ukraine, Ukrainian authorities declared Zatulin persona non grata in June 2006 based on a provision of Ukrainian law which states that foreigners are prohibited to enter the country if they violated Ukrainian law during their previous stay. The visa ban was lifted two years later.

In 2015, a criminal investigation relating to Zatulin's activities was launched in Ukraine, and in 2017 his name was put on the wanted list as suspect in jeopardizing the integrity and inviolability of borders and planning, preparation and conduct of war.

Zatulin also has caused tensions in South Caucasus by visiting the disputed Nagorno Karabakh region.

The Estonian government is scheduled on Thursday to discuss a proposal by Minister of Foreign Affairs Sven Mikser (SDE) to impose sanctions on the 49 individuals listed on the so-called Magnitsky List. It is unknown whether or not Zatulin is among those named on the list.