Russia’s most prominent opposition figure, Alexei Navalny, has been taken from jail to a hospital in Moscow.
Officials said Mr Navalny was in a satisfactory condition but his personal doctor said he may have been poisoned.
His spokeswoman earlier suggested he may have have had an allergic reaction, but she said he had not experienced one before.
Mr Navalny was jailed for 30 days last week after calling for unauthorised protests, which took place on Saturday.
Nearly 1,400 people were detained during the demonstrations against the exclusion of opposition candidates from local elections.
The European Union criticised the “disproportionate” use of force against the protesters, saying it undermined the “fundamental freedoms of expression, association and assembly”.
Media reports said about 20 people, including journalists, were also detained after gathering outside the prison hospital on Sunday night where Mr Navalny was being treated.
What do we know about Mr Navalny’s condition?
While in prison over the weekend, Mr Navalny reportedly began suffering from acute swelling, discharge from his eye and rashes on his neck, back, chest and wrists.
His former campaign manager, Leonid Volkov, said he recalled having a similar reaction while serving a prison sentence in the same jail cell for breaking protest laws.
The hospital described Mr Navalny’s condition as satisfactory.
Mr Navalny’s personal doctor, Anastasia Vassilieva, said earlier that none of the opposition figure’s family or lawyers had been told his diagnosis.
In a Facebook post, Ms Vassilieva complained that she had been barred from visiting Mr Navalny. But based on what she saw of him through a door, she said he may have been injured by a “chemical substance from a third person”.
She said that her suspicions were being fuelled by “certain officials… acting strange”.
“No one is looking for the cause [of his illness], doctors are denied access. There are lies all around,” she wrote.
Who is Alexei Navalny?
The 43-year-old made his name in Russia as a grassroots anti-corruption campaigner.
He led the country’s biggest street protests against President Putin in 2011 and has repeatedly been jailed, usually for his involvement in unauthorised demonstrations.
Mr Navalny suffered a serious chemical burn to his right eye in 2017 after he was assaulted with antiseptic dye.
He attempted to stand in last year’s presidential race but was barred because of previous fraud convictions in a case he says was politically motivated.
What happened during the protests?
Thousands of Russians took to the streets last Saturday to demand fair elections. The demonstrations came after 30 opposition candidates were barred from standing in local races this September.
Officials said the candidates had failed to collect enough valid signatures to stand, but opposition groups argued that the barring was politically motivated.
Mr Navalny helped to organise the demonstrations. Officials said they had arrested nearly 1,400 people – making it one of the biggest crackdowns in recent years.
Images from Saturday showed police in riot gear pushing crowds from the mayor’s office in central Moscow.
A number of protesters could be seen bleeding, while at least two members of the security forces reportedly received eye injuries from pepper spray.
Alexei Navalny: Jailed Russian opposition head taken to hospital