Moscow, Russia (AFP) — Russian authorities announced a manhunt on Saturday after six convicts tunnelled their way out a correctional facility.

Four of the six fugitives have now been detained, while local law enforcement are in hot pursuit of the remaining two.

“I realise that the news may cause concern, but I ask you not to panic,” said Igor Artamonov, governor of the western Lipetsk region.

“Security forces are continuing efforts to track down and detain the criminals,” he added.

Prison guards were alerted to their disappearance after carrying out a routine inspection.

“In general regime penal colony No. 2, an underground tunnel was discovered during a patrol of the premises,” the prison service of the Lipetsk region said.

“Immediately a count of convicts got underway, which revealed the absence of six inmates,” it added.

It did not reveal their identities, but said in a statement the suspects were “from Central Asia”.

Four of the escapees were detained, two of whom were caught in the neighbouring Tambov region, the local governor said.

“The search for the remaining two criminals continues,” he said.

The Lipetsk region is about 300 kilometres (190 miles) south of Moscow.

Russia has one of the highest prison populations in the world, totalling more than 400,000 people last year, but numbers have decreased as convicts are sent to fight in Ukraine.

Prison escapes are relatively rare in Russia and those who manage to break out are often quickly caught.