SIMFEROPOL, July 17. /TASS/. Speleologists have found a possible extension of the newly discovered solutional cave in Crimea that contains fossil bones of mastodons and mammoths, Gennady Samokhin, chairman of the Russian Union of Speleologists and academic secretary of the Russian Geographical Society’s Crimean branch, said on Tuesday.

Crimean Prime Minister Sergei Aksyonov said earlier he had initiated the setting up of a commission to examine the cave, which had been discovered near the township of Zuya, Belogorsk district, while building a section of the Tauride federal road. All works in the area adjoining the cave were suspended until completion of the research, since construction experts point out the risk of a possible collapse of the ground. Experts said the cave could have evidence of early human activity and help get a clearer picture of what Crimea looked like before the Ice Age.

"A number of cavities have already been discovered. A 600mm hole will be drilled so that speleologists could get inside. It may be done in a couple of days. Obviously, it is a single geological system occasionally blocked by argillaceous and dumped deposits. In the prehistoric times, the cave was part of a single water-bearing layer," Samokhin told TASS.

According to Samokhin, the cave may stretch tens of kilometers long. "Specialists are now making its tomographic image with the help of special equipment. They are making vertical sounding to explore the cave’s possible extension on the other side of the highway. It’s too early to say how long the cave might be - it may be from to tens of kilometers long," he said.

However, according to Samokhin, exploration of the cave is not an easy job because of oxygen deficiency. That is why it has been decided to limit the time of stay inside the cave by two hours for three to four people.

Air samples taken from the cave indicate an oxygen content of 18% while the minimal permissible levels for a human being are from 19.5 to 21%

"Strict restrictions have been imposed in terms of the stay inside the cave. Thus, only three or four people are allowed to stay at one place for not more than two hours," he said. "I came down to the cave and can say that when you stay there longer you develop breathing problems, increased sweat secretion, easy fatiguability."

According to the state contract for construction of the Tauride federal road, its first section from the Kerch Strait Bridge to the regional capital Simferopol is to be opened for regular traffic in December. The entire length of the route from the city of Kerch on the Sea of Azov to Sevastopol is to go into operation in December 2020.