Fears for NGOs in Russia as tax raids multiply
An earlier protest against the law on NGOs, saying that the amendments to it mark the road to fascism
Senior EU officials have voiced concern as checks by Russian tax inspectors on foreign-funded non-governmental organisations multiply.
On Wednesday searches took place at the Moscow offices of Human Rights Watch and Transparency International.
Two German political NGOs were searched earlier in Moscow and St Petersburg.
Foreign Minister Guido Westerwelle summoned the number two diplomat at the Russian embassy in Berlin to relay his "concern over the concerted action".
Other NGOs in Russia have also been searched by prosecutors and tax inspectors in recent weeks, with reports that hundreds may have been affected across the country.
A Russian law passed in July obliges foreign-funded NGOs involved in political activity to register as "foreign agents". Failure to comply is punishable by heavy fines and even a two-year prison sentence.
The Kremlin says the controversial law is needed to protect Russia from outside attempts to influence internal politics, but critics argue it is a mechanism to crush dissent after the mass protests against the ruling United Russia party early last year.
Confirming that a search was under way, Human Rights Watch official Rachel Denber told Russia's Interfax news agency: "This wave of checks is pressure on civil society in Russia."
Both the Konrad Adenauer Foundation (KAS) in St Petersburg and the Friedrich Ebert Foundation (FES) in Moscow were investigated earlier.
The KAS think tank is linked to German Chancellor Angela Merkel's Christian Democrats, while the FES is close to Germany's main opposition Social Democrats.
"Hampering the activity of German foundations could inflict lasting damage on bilateral relations, " a German diplomat told Spiegel Online.
"We have made this clear to the Russian side."
The Christian Democrats said the Russian authorities had seized computers from the KAS office in a "totally unacceptable" action.
"The political foundations from Germany are making an important contribution to the development of democratic structures, the building of a state based on law and the encouragement of civil society, " CDU general secretary Hermann Groehe said in a statement.
EU foreign policy chief Catherine Ashton said on Tuesday she was "concerned with the ongoing actions of the authorities against the NGO community" in Russia.
Among the NGOs targeted was the human rights organisation Memorial, which was visited by Russian officials three times inside a week. Amnesty International was also targeted.
A number of NGOs have challenged the authorities to justify the searches.