Russian border guards have seized more than 4,000 endangered wild tortoises after they were smuggled out of Kazakhstan, officials said.

Traffickers drove the 4,100 Central Asian tortoises, which are classed as globally vulnerable, across the border into Russia's Orenburg region in a trailer where they were disguised as cabbages, the interior ministry said Tuesday.

Their market value was estimated at 7.8 million rubles (about $117,000).

Investigators placed the reptiles under the care of a college in Orenburg, where students and staff fed them for a month.

"They were put into an old sports hall and we had to feed them every other day for over a month while the paperwork was being prepared," said Sergei Ryabtsov, who coordinated the rescue effort at Orenburg Pedagogical University.

"They ate cabbage, squash, fruit -- anything with high water content," he said.

Video footage released by the interior ministry showed the dilapidated sports hall overrun by the brown tortoises chomping on pieces of vegetables.

The university had experience in caring for smuggled tortoises: in 2016 its students had to feed over 8,000 of the reptiles in a similar situation.

After the paperwork was prepared and the tortoises were checked for parasites, they were transported in cardboard boxes and released in southern Kazakhstan.