(Reuters) - A Russian general in charge of personnel issues has been detained on suspicion of engaging in criminal activity, Tass news agency reported early on Tuesday, quoting a source in the security services.

News of the arrest of Lieutenant-General Yuri Kuznetsov was made public barely a day after President Vladimir Putin oversaw major changes in Russia's defence establishment, including the dismissal and transfer of Defence Minister Sergei Shoigu.

The security source told Tass that Kuznetsov, head of the ministry's body overseeing personnel issues, had been detained "on suspicion of criminal activity".

"The investigation of the case is being conducted by the main military investigative body of Russia's Investigative Committee," the source told Tass, referring to Russia's most important investigative institution.

"The investigator has already approached the court on selecting preventive conditions for the general in the form of upholding his detention."

Tass provided no further details.

Pro-government military bloggers reported that Kuznetsov had failed to appear at work due to the investigation.

The popular blogger site Rybar suggested the investigation could be linked to his previous work within the Russian General Staff dealing with state secrets.

A former deputy defence minister, Timur Ivanov, has been in detention since last month on allegations of receiving a large bribe in connection with military construction projects.

Shoigu was replaced on Sunday as defence minister by civilian economist Andrei Belousov and was put forward by the president as secretary of Russia's Security Council.

The head of the Security Council, Nikolai Patrushev, is to get a new, as yet unannounced, job.

The changes, certain to be approved by parliamentarians, are the most significant Putin has made to the military command since the February 2022 invasion of Ukraine.

(Reporting by Ron Popeski; Editing by Stephen Coates)