The European Union's foreign policy chief says raids by Russian authorities on non-governmental organizations operating in the country are "deeply troubling."

EU High Representative Catherine Ashton said Tuesday the months-long series of crackdowns on foreign-funded NGOs in Russia are being carried out under "vague legal grounds" and are "worrisome since they seem to be aimed at further undermining civil society activities in the country."

The European leader's statement came after authorities raided the Moscow headquarters of Amnesty International Monday during an unannounced "audit," The New York Times reported.

An Amnesty International official told the newspaper government agents demanded a list of documents already on file with the government and were followed by state-controlled media who allegedly harassed staff members.

Referring to the Russian Parliament's move to impose strict new rules governing international aid groups and the imprisonment of the "Bolotnaya 17" anti-government protesters, Ashton warned the human rights trend in the country was foreboding.

"The ongoing raids, taken together with the recent package of legislation that curtails the civil freedoms of Russian population, an upsurge in prosecution of civil society activists, the Bolotnaya and other political trials, as well as lack of action in some prominent cases of human rights abuses, constitute a trend that is deeply troubling," she said.

Ashton praised the work of the NGOs, calling them "indispensable in a vibrant democracy, thereby contributing significantly to the modernization of society."

The Russian government has been clamping down on international non-profits operating in the country, forcing some, depending on their funding sources, to register as "foreign agents."

The Bolotnaya case -- in which 17 young men protesting what they called the fraudulent re-election of President Vladimir Putin were arrested May 6 in Moscow's Bolotnaya Square -- the imprisonment of the punk rock band Pussy Riot and the 2009 death in prison of whistle-blowing lawyer Sergei Magnitsky have all exacerbated human rights tensions.

Since the NGO law was passed in July, the Kremlin has stopped cooperating with the U.S. Agency for International Development, which closed its office in Moscow.

The human rights situation in Russia was among the concerns brought up with Putin and Russian Foreign Minister Sergei Lavrov during a December Russia-EU Summit attended by Ashton, European Council President Herman Van Rompuy and European Commission President Jose Manuel Barroso.

In the run-up to the summit, activists such as Hugh Williamson, Europe and Central Asia director of Human Rights Watch, urged the European Union to "convey a clear sense of alarm at the crackdown of the past six months" while meeting with the Russian leaders.

The European Union, he said, "should press the Russian leadership to stop trying to choke off free speech and assembly and any sign of dissent," condemning the NGO law as trying to "demonize" the groups in the public eye "as spies and traitors."

Another law, adopted in November, expands the definition of treason "in ways that could criminalize international human rights advocacy," Williamson said.

The European Parliament in December overwhelmingly adopted a report on Russia that also took the Kremlin to task on human rights, even as Brussels and Moscow continue work on replacing their 1997 Partnership and Cooperation Agreement.