By Evan Perez and Paul Cruickshank
U.S. authorities are working with Russia and other countries to try to disrupt possible threats related to the Sochi Olympics, in addition to the toothpaste tube terror concern, a U.S. intelligence source said.
The official said the threats varied in credibility.
The biggest source of those threats is the group Imarat Kavkaz in Russia, which has publicly said it will try to disrupt the Games, the official said Thursday.
The concern about the threat of toothpaste or cosmetic tubes being used to hide explosives originated "from the leader of the Chechen rebel extremists," said U.S. House Homeland Security Committee Chairman Michael McCaul, a Texas Republican.
"That's where the plot hatched out of," McCaul said in an interview with CNN's Wolf Blitzer.
Separately, the top Democrat on the House Intelligence Committee, C.A. "Dutch" Ruppersberger, told CNN the information passed on to U.S. authorities about explosives disguised as toothpaste and cosmetics mainly came from "chatter."
But he said the United States was right to act out of caution because often, chatter indicates a real threat.
Concern about the threat prompted French officials to arrest two Chechen women this week, the U.S. intelligence source said.
Eric Pelletier, the national security correspondent for the French newspaper L'Express, said French intelligence began looking into the connection of the women to terrorism in December after information from a foreign intelligence service warned of a "black widow" threat.
The women, who were not identified, were arrested in La Roche-sur-Yon and Stasbourg.
One was the widow of Chechen Jihadist Khamzat Chemilev, known as the "emir of Grozny" who was killed battling Russian security services in August 2010, and the other was his sister, sources told Pelletier.
At the same time, Russia sent similar communiques to other European countries about concerns that Chechens and others planned to return to Russia to carry out an attack. This seems to have been largely preventive.
Pelletier said the sources indicated the information came from Russian intelligence.
There was concern the women in France would travel to Russia - and more specifically the Sochi area - to launch suicide attacks during the Olympics.
While the initial warning to the French did not mention a concern about explosives in toothpaste tubes, a subsequent intelligence alert sent to Western intelligence services in January regarding the toothpaste threat raised the level of concern about the two women.
In the French arrests this week, authorities were looking for evidence connected to the threat involving toothpaste and cosmetic tubes, Pelletier said.
But after the arrests, French law enforcement found nothing to suggest the women were a threat or had plans to travel to Russia.
Chemilev's widow was let go and his sister was to appear before French prosecutors in Paris later on Friday.
Investigators are interested in the contents of her computer and are likely to place her under formal judicial investigation, according to Pelletier.
Arrests of suspected Chechen extremists were also reported in Austria, but according Helmar Dumbs, a national security reporter for Die Presse in Austria, the Interior Ministry denied there was any connection to the use of toothpaste container explosives on planes.
The Austrian suspects remain a concern although they have been cleared, McCaul said.
"There were six Austrians detained and questioned and, for lack of evidence, let go," McCaul said in the CNN interview. "They are under surveillance. Currently, they are of a concern, obviously."