LONDON (Reuters) -Russian soldiers who seized the site of the Chernobyl nuclear disaster drove their armoured vehicles without radiation protection through a highly toxic zone called the "Red Forest", kicking up clouds of radioactive dust, workers at the site said.
The two sources said soldiers in the convoy did not use any anti-radiation gear. The second Chernobyl employee said that was "suicidal" for the soldiers because the radioactive dust they inhaled was likely to cause internal radiation in their bodies.
Ukraine's state nuclear inspectorate said on Feb. 25 there had been an increase in radiation levels at Chernobyl as a result of heavy military vehicles disturbing the soil. But until now, details of exactly what happened had not emerged.
The two Ukrainian workers who spoke to Reuters were on duty when Russian tanks entered Chernobyl on Feb. 24 and took control of the site, where staff are still responsible for the safe storage of spent nuclear fuel and supervising the concrete-encased remains of the reactor that blew up in 1986.
Both men said they had witnessed Russian tanks and other armoured vehicles moving through the Red Forest, which is the most radioactively contaminated part of the zone around Chernobyl, around 100 km (65 miles) north of Kyiv.
The regular soldiers one of the workers spoke to when they worked alongside them in the facility had not heard about the explosion, he said.
Asked to comment on the accounts from Chernobyl staff, Russia's defence ministry did not respond.
The Russian military said after capturing the plant that radiation was within normal levels and their actions prevented possible "nuclear provocations" by Ukrainian nationalists. Russia has previously denied that its forces have put nuclear facilities inside Ukraine at risk.
The site got its name when dozens of square kilometres of pine trees turned red after absorbing radiation from the 1986 explosion, one of the world's worst nuclear disasters.
A vast area around Chernobyl is off limits to anyone who does not work there or have special permission, but the Red Forest is considered so highly contaminated that even the nuclear plant workers are not allowed to go there.
The Russian military convoy went through the zone, the two employees said. One of them said it used an abandoned road.
"A big convoy of military vehicles drove along a road right behind our facility and this road goes past the Red Forest," said one of the sources.
"The convoy kicked up a big column of dust. Many radiation safety sensors showed exceeded levels," he said.
Valery Seida, acting general director of the Chernobyl plant, was not there at the time and did not witness the Russian convoy going into the Red Forest, but he said he was told by witnesses that Russian military vehicles drove everywhere around the exclusion zone and could have passed the Red Forest.
"Nobody goes there ... for God's sake. There is no one there," Seida told Reuters.
He said workers at the plant told the Russian service personnel they should be cautious about radiation, but he knew of no evidence that they paid attention.
"They drove wherever they needed to," Seida said.
After the Russian troops arrived, the two plant employees worked for almost a month along with colleagues until they were allowed to go home last week when Russian commanders allowed replacements for some of the staff to be sent in.
Reuters could not independently verify their accounts.
They were interviewed by phone on Friday on condition of anonymity because they feared for their safety. The next day Russian forces seized the town Slavutych near Chernobyl, where most plant workers live.
Seida and the mayor of Slavutych said on Monday that Russian forces had now left the town.
Reuters was not able to independently establish what the radiation levels were for people in the immediate proximity of the Russian convoy that entered the Red Forest.
Ukraine's State Agency of Management the Exclusion Zone said on Feb. 27 that the last record it had on a sensor near nuclear waste storage facilities, before it lost control over the monitoring system, showed that the absorbed dose of radiation was seven times higher than normal.
The International Atomic Energy Agency (IAEA) said on Feb. 25 that radiation levels at the Chernobyl site reached 9.46 microsieverts per hour but remained "within an operating range" recorded in the exclusion zone from the moment of its creation and posed no threat to the general population.
The safe levels, by IAEA standards listed on the agency's official website, are up to 1 millisievert per year for the general population and 20 millisievert per year for those who deal with radiation professionally - where 1 millisievert is equal to 1,000 microsieverts.
On March 9, the IAEA said it stopped receiving monitoring data from the Chernobyl site. It gave no response on Monday to the workers' allegations.
The Chernobyl exclusion zone is still considered by Ukrainian authorities to be dangerous. Entering the disaster site without permission is a crime under Ukrainian law.
In the weeks the two plant employees were sharing the complex with Russian troops, they also said they saw none of them using any gear that would protect them from radiation.
Specialists from the Russian military who are trained in dealing with radiation did not arrive at the site until about a week after Russian troops arrived, the workers said. They said the Russian specialists did not wear protective gear either.
One of the employees said he had spoken to some of the rank-and-file Russian soldiers at the plant.
"When they were asked if they knew about the 1986 catastrophe, the explosion of the fourth block (of the Chernobyl plant), they did not have a clue. They had no idea what kind of a facility they were at," he said.
"We talked to regular soldiers. All we heard from them was 'It's critically important infrastructure'. That was it," the man said.
The accounts about Russian troops in Chernobyl chime with other evidence suggesting the invasion force sent into Ukraine was not fully prepared for what they encountered.
The Kremlin says that what it calls its special military operation in Ukraine is going to plan and is on schedule.
But Ukrainian officials and their Western allies say Russia's initial thrust deep into Ukrainian territory stalled after encountering logistics problems and facing stiffer-than-expected Ukrainian resistance.
Russia initially said only professional soldiers were sent in but reversed itself and said that conscripted men had been inadvertently deployed, with some of them taken prisoner.
Ukrainian intelligence has said Russian soldiers often use open radio frequencies or mobile phones to communicate among themselves, which means Kyiv's forces could eavesdrop on their conversations.
Video footage shared on social media in Ukraine showed multiple cases of Russian military vehicles that had no combat damage but which had been abandoned after breaking down or running out of fuel.
Washington assesses that Russia is suffering failure rates as high as 60% for some of the precision-guided missiles it is using to attack Ukraine, three U.S. officials with knowledge of the intelligence told Reuters last week.
(Editing by Alison Williams)