UK and US diplomats have denied allegations from Moscow that non-governmental organisations from their countries are spying on Russia.
Patrushev said opponents wanted to weaken Moscow's influence
Russian security chief Nikolai Patrushev said on Thursday UK charity Merlin and the US Peace Corps were among NGOs used to gather information.
The Saudi Red Crescent and an organisation from Kuwait were also accused of espionage.
Mr Patrushev said foreign NGOs were also plotting revolution in Belarus.
At least $5m (£2.6m) has been funnelled to opposition groups in Belarus for 2005, he said.
The US has called Belarus "Europe's last dictatorship".
The BBC's Steve Rosenberg in Moscow says Mr Patrushev's comments reflect a growing belief among Russians that the West is plotting to undermine their country.
But a statement from the US embassy in Moscow denied the allegations.
"The US government categorically rejects charges... that American non-governmental organisations are being used to carry out intelligence operations against Russia under the guise of charitable and other activities," it said.
A similar statement by the UK embassy described the allegations as "wholly false".
Speaking to Russia's parliament on Thursday, Mr Patrushev - who heads the FSB, a successor to the Soviet KGB - said Russia's opponents were trying to weaken Moscow's influence in the former Soviet Union and elsewhere.
"Foreign secret services are more actively using unconventional methods in their work and are using the teaching programmes of various NGOs to promote their interests."
The US Peace Corps, one of the organisations mentioned, pulled out of Russia in 2002 amid spying allegations.
The British medical group Merlin has been helping to fight TB in Russia for nearly a decade.