Russian activists are criticizing the Kremlin for a new law that labels non-governmental organizations receiving financial support from abroad as “foreign agents.”

The Kremlin said Saturday that President Vladimir Putin had signed the controversial measure, which cleared parliament earlier this month.

The law applies to NGOs engaging in political activities. Opponents say it is a Kremlin attempt to silence critics.

Lev Ponomarev, the head of one of Russia's oldest NGO's , says his organization will not obey the new regulation.

Moscow Helsinki Group leader Lyudmila Alexeyeva said her group will turn down foreign funding in an attempt to work around the law.

Earlier this month, the U.S. State Department expressed “deep concern” about the provision, which prompted a Russian rebuke for what the government called foreign interference.

The new measure took effect a month after President Putin signed a bill imposing huge fines for participating in unauthorized demonstrations.