A Russian court on Wednesday ordered that Kremlin critic Andrei Pivovarov be held in pre-trial detention for two months, his allies said from the courtroom.
"Andrei Pivovarov has been detained for two months," allies wrote on his Facebook account from the courtroom, describing the ruling as a "pretext" to bar the activist from running in upcoming parliamentary elections.
Pivovarov, the former executive director of Open Russia, a just disbanded pro-democracy group, was pulled off his Warsaw-bound flight on Monday.
The 39-year-old faces up to six years in prison for his involvement in an "undesirable" organization.
On Tuesday, police detained opposition politician Dmitry Gudkov after conducting raids on homes of his allies and relatives.
The 41-year-old former opposition lawmaker faces up to five years in prison for allegedly failing to pay a debt under an old lease agreement.
Gudkov is likely to be formally charged on Wednesday, said human rights association Agora whose lawyer represents him.
Putin's spokesman Dmitry Peskov said the detentions were a purely legal matter.
"The charges put forward by law enforcement have nothing to do with politics," he told reporters.
Russian authorities had for years tolerated opposition groups including Navalny's political movement but Kremlin critics say authorities are moving to remove any vestiges of dissent.