Russia has condemned as blasphemous the removal by Estonian authorities of a contentious Red Army war memorial.
Russia says the statue honours soldiers who fought Nazi Germany
Estonia was mocking the dead, said Russian Foreign Minister Sergei Lavrov. However, many Estonians saw the statue as a reminder of Soviet rule.
One person was killed early on Friday as the statue was removed from the capital, Tallinn.
In the evening police used tear gas and water cannon as they clashed with protesters throwing Molotov cocktails.
Officers had moved in to disperse the protesters from the site but correspondents say there is no sign of the crowd - more than a 1,000 strong, leaving. Protesters have set fire to posters and trees.
The removal had provoked angry condemnation from Russian officials and lawmakers.
1918: Estonia gained independence from Russia
1940: Forcibly incorporated into Soviet Union
1941-1944: Occupied by Nazi Germany
1944: Soviets return as Nazis retreat
1991: Gains independence as Soviet Union collapses
1994: Last Russian forces leave Estonia
Now: Ethnic Russians make up quarter of Estonia's 1.3m people
Mr Lavrov said Russia would "take serious steps" following the removal and Russia's Federation Council (upper house) called for diplomatic relations with Estonia to be cut.
Estonia's government would not reveal where it took the six-foot (1.83m) statue, but spokesman Martin Jasko said it would ultimately be placed at the military cemetery in Tallinn.
The memorial, a bronze statue of a Soviet soldier, was erected in 1947. The remains of Soviet soldiers are thought to be buried nearby.
Estonian officials said it had to be moved to a cemetery because the site attracted both Russian and Estonian nationalists.
By Thursday evening, around 1,000 demonstrators had gathered as police sealed off the site ahead of the removal.
The memorial has inspired violence between communities
There were reports of looting and vandalism, and police used tear gas and a water cannon when a group tried to break through a cordon around the monument. Several police were among the injured, reports said.
More than 300 of the mostly ethnic Russian demonstrators were arrested during the overnight clashes.
"The aim of the government move was to prevent further similar gross violations of public order, which pose a real threat to citizens' health and property," an Estonian government statement said.
Ethnic Russians, who make up more than a quarter of Estonia's 1.3 million population, say that the statue commemorates Red Army soldiers who died fighting Nazi Germany.
"International organisations should examine [the events in Tallinn] in all seriousness and take any necessary steps to cool the ardour of the Estonian authorities," RIA Novosti news agency quoted Russian Foreign Ministry spokesman Mikhail Kamynin as saying.
But on Thursday, Estonian Prime Minister Andrus Ansip said the relocation of the memorial was a matter for Estonia alone.
"We don't consider it necessary to hold deep discussions with the Russian authorities over the internal affairs of Estonia," he said.