The leaders of the European Union and Russia have traded sharp criticism over human rights, at a summit that exposed the divisions between the two sides.
The tension at the summit was palpable, one EU official said
German Chancellor Angela Merkel expressed alarm at the detention of activists intending to protest against the Russian government.
Vladimir Putin retorted that Estonia's ethnic Russians were being persecuted.
Correspondents said the exchanges just illustrated the souring mood between the EU and its eastern neighbour.
There are a number of prickly issues between the two, including trade, energy supplies and Kosovo.
In a break with previous practice, no joint declaration was prepared before the summit at Volzhsky Utyos government resort, near the Russian city of Samara.
If the atmosphere at the post-summit news conference was anything to go by, the relationship has reached a new low, says the BBC's Rupert Wingfield-Hayes in Moscow.
President Putin turned the tables on the EU, accusing members Estonia and Latvia of violating the human rights of their Russian minority.
"We believe this is unacceptable and unworthy of Europe," he said.
It follows Estonia's removal last month of a World War II monument to Red Army soldiers, which led to riots and the death of one ethnic Russian.
In a BBC interview after the summit, Russian Foreign Minister Sergei Lavrov said the future status of Kosovo should be decided by the Serbian people.
He said those who thought it could be determined by Russia, the EU and the US were burdened by colonial instincts.
EU leaders have recently expressed alarm about Russian threats to veto a UN Security Council resolution proposing Kosovo's de facto independence from Serbia.
Mr Lavrov said: "It's a case which, according to the United Nations Security Council Resolution 1224, adopted by consensus, supported by Russia, by the European Union, and by the United States, must be resolved in negotiations between Belgrade and Pristina."
European Commission President Jose Manuel Barroso warned Russia that any action taken against an individual EU state would be considered action against the whole bloc.
"It is very important if you want to have close co-operation to understand that the EU is based on principles of solidarity," he said.
Mrs Merkel, whose country holds the EU's rotating presidency, then stepped in, complaining that opposition activists had been prevented from travelling to the summit venue to take part in a protest.
"I'm concerned about some people having problems in travelling here," Mrs Merkel said.
"I hope they will be given an opportunity to express their opinion."
A number of leading anti-Putin activists, including the former chess champion Garry Kasparov, had passports confiscated and were detained at Moscow's Sheremetyevo airport.
The authorities said they had false travel documents.
Several foreign journalists were also reportedly prevented from travelling.
Nevertheless, some protesters - estimated variously between 100 and 500 - gathered at a square in Samara and marched, chanting slogans like "Russia without Putin!"
"I don't agree with what's happening in Russia today. I want another Russia, a free one," said Natalya Sorochan, 27.
A perceived increase in Russian authoritarianism is one of the thorns in the side of EU-Russian relations, correspondents say.
Mr Barroso said the EU's "sacred principles" included "democracy, freedom of the press, freedom of association, freedom of demonstration".
Another testing issue is Russia's ban on meat imports from Poland over apparent food safety issues.
Poland rejects the ban, and says it will veto any new strategic partnership between the EU and Russia, until it is lifted.
Also souring relations are the cutting of Russian oil supplies to Lithuania in a separate row.