At least six Central Asian nationals were detained on Wednesday in St. Petersburg for recruiting individuals for terror related crimes in Russia, the Investigative Committee said on Wednesday.

There was no evidence of their ties with the perpetrator of Monday's subway terror attack that left 14 persons dead, TASS news quoted the Investigative Committee as saying.

The investigators have detained "six Central Asian Republics natives who came to Russia for earnings", the committee said.

They had been recruiting mostly natives of Central Asian Republics in St. Petersburg since November 2015 for terror related crimes involving Jabhat al-Nusra and the Islamic State militant group.

"Russia's Investigative Committee will thoroughly check all the ties and the contacts of the persons detained but (right now) the investigation has no data on the detainees' link and acquaintance with the perpetrator of the St. Petersburg attack," it said.

The committee said the suspects were seeking to involve recruited citizens in the activity of other illegal armed formations, including on the territory of foreign states.

"Searches are being held at the suspects' living places, in the course of which investigators are seizing Islamist extremist literature, the items and documents important for investigating the criminal case," it said.

Investigators are currently deciding on arresting the detainees and bringing charges against them.

Measures are also under way to identify and bring the detainees' accomplices to criminal liability.

Meanwhile, the law enforcement agencies said Akbarzhon Jalilov, who is suspected of carrying out the attack, had a clean record.

"He had no criminal record and had never been on law enforcement's radar. His name was not among extremists in the intelligence database," the source said.

"Upon becoming a Russian citizen, there were no problems with him. Citizenship was granted to him based on legally established procedures," he added.