MOSCOW -- Migrant advocates are warning foreign workers in St. Petersburg to lie low as increased police document checks stoke fears of a wider crackdown on Central Asian and Caucasus migrants following the identification of a Kyrgyz-born Uzbek man as the chief suspect in this week's subway attack.

The Russian Investigative Committee on April 4 identified Akbarjon Jalilov, 22, as the leading suspect in the April 3 bombing that killed 14 people and injured 50.

Some rights activists in Moscow have predicted a clampdown targeting migrant workers, particularly those from Central Asia. They point to what they say was negative stereotyping when Russian media twice published photographs wrongly identifying men from Muslim former Soviet regions as being the organizers of the attack.

REN-TV first published a picture and then video of a bearded man in dark Islamic garb near the site of the explosion widely circulated online. After learning of the accusations from the media, the man later turned himself in to a police station to clear his name and was released after being questioned.

He was identified as Andrei Nikitin, a trucker from the central region of Bashkortostan and a retired paratrooper of the Russian armed forces.

Nikitin told the website Islam News on April 4 that he was flying from St. Petersburg to Moscow but couldn't take his connecting flight to Orenburg when fellow passengers refused to fly with a man they believed was the organizer of the attack.

The St. Petersburg news site Fontanka.ru on April 3 strongly suggested in a report that 22-year-old Maksim Aryshev, a citizen of Kazakhstan, was the chief suspect, but the Kazakh Foreign Ministry later denied this, instead saying he was a victim.

Ali Charinsky, a Moscow-based activist, decried the stereotyping in an emotional post on Facebook: "The conclusion is obvious that Muslims are going to suffer whoever carried out this [bomb attack]."

Millions of migrants from the former Soviet regions of Central Asia and the North and South Caucasus -- where jobs are often scarce -- work in Russia, often in low-paying jobs and often without authorization.

In the past, Russian authorities have carried out targeted crackdowns in what analysts have seen as an effort to respond to rising nationalist, xenophobic sentiments in the country.

Migrant Warnings

Azamat Mamyshev, an aide to the honorary Kyrgyz consul in St. Petersburg, said there had not been uptick in violence by skinhead radicals or others so far.

"But our [citizens] are calling, and are worrying about their jobs," he told RFE/RL's Kyrgyz Service. "We are warning them not to go outside more than they have to, for them not to walk around on their own, for them not to get held up late. There are currently ramped up [police] checks, the times are not calm."

On April 3, one Twitter user posted an image, alleging that riot-police officers had entered a movie theater in St. Petersburg and were leading non-Slavic looking people out. That report could not be confirmed.

Karim, an Uzbek community worker who asked not to be identified by his surname, told RFE/RL's Uzbek Service that he had witnessed police checking passports of citizens of Kyrgyzstan. "People from Central Asia are considered of particular concern," he said.

According to official statistics, 13,000 Kyrgyz migrants work in St. Petersburg, although the real figure is thought to be nearer twice that.

"We are warning [citizens] to constantly carry documents with them, and not to associate with suspicious groups," Raimkul Attokurov, head of the Kyrgyz diaspora in Moscow, told RFE/RL's Kyrgyz Service. "In the metro, in public places where there are lots of people, they [the police] are checking people of non-Slavic appearance. I've seen it for myself."

In comments to RFE/RL's Uzbek Service, Mahmud Mamadmuminov, an Uzbek journalist living in St. Petersburg, noted that Kyrgyz citizens required less documentation to work legally in Russia. "Now I'm concerned that security services will intensify operations inside our communities," he said.

Bakhrom Khamroyev, a Moscow-based migrant rights worker for the human rights group Memorial, said there were already stepped-up police checks around the country and that he expected a further clampdown. "Even I feel the pressure and I feel the mood of the people," said Khamroyev, who is an ethnic Uzbek.

He recounted an incident from April 4 when on the subway he witnessed a drunk Russian man accost an ethnic Armenian man carrying a bag, demanding he open it -- insinuating he might be a suicide bomber. "This is how events are going to develop with this fake information from the authorities and the Russian media," he said.

At The Mosque

At Moscow's new central mosque, which was opened by President Vladimir Putin to great fanfare in September 2015, Rasul, 37, said he had only just arrived from Kyrgyzstan and had not yet had time to find a job.

Speaking in broken Russian, he said after the explosion one of his first thoughts was "that they're going to start checking all migrants."

Akhmed, 23, who traveled with his brother to Moscow where they are working as builders to earn money for a sick relative back home, was at the mosque on April 4 to eat at the local cafe.

He said he was "deeply pained" by the attack, but that he immediately wondered if a crackdown on migrants would follow. "Yesterday, of course I had that thought -- that there could be something from the law," he said.