According to an AFP report, Cecily planned to leave Lisbon and reach Vladivostok.
However, she was arrested and accused of attempting to illegally cross the China-Russia border when she was 200 kilometers from her destination.
France's consulate general in Moscow has contacted the Russian government over the incident.
This incident is reminiscent of the case of another French citizen, Laurent Vinatier, who was arrested in Russia last year.