Kiev, 1 September 2022 (dpa/MIA) - An International Atomic Energy Agency's (IAEA) observer mission arrived at the embattled Zaporizhzhya nuclear power plant in southern Ukraine on Thursday, amid worries that the Russian invasion in Ukraine could result in a nuclear disaster. The Ukrainian nuclear authority Enerhoatom confirmed the arrival on its Telegram channel on Thursday. The trip is an effort to secure Europe's largest nuclear power plant, in a country with strong memories of the Chernobyl nuclear disaster from 1986, one of the worst in world history. The IAEA group has 14 members and wants to assess the situation at the plant, which has six reactors and a net power capacity of 5,700 megawatts. It was occupied by Russian forces in March, shortly after the invasion started. Beforehand, about 10,000 people worked there. Underscoring the current danger, there were reports of artillery fire upon the nearby city of Enerhodar before the team's arrival. IAEA boss Rafael Grossi said he had been updated on the risks before leaving and assured that nothing would stop them. Kiev accused Russia of targeting the route of the IAEA group. Russia responded with accusations that Ukrainian forces had attempted a landing operation near the reactor, along the Dnipro River, which was repulsed. Video released showed Russian helicopters above Enerhodar. Enerhoatom also reported that a reserve power supply for the plant was severed due to the shelling, resulting in one reactor being powered down. "As a result of renewed mortar fire by Russian occupation forces at the site in Zaporizhzhya nuclear power plant, emergency protection was activated and the operating fifth reactor was shut down," Enerhoatom announced on its Telegram channel. Reactor number six, which supplies the plant with the necessary electricity, is still in operation. The information cannot be independently verified. The Russian and Ukrainian sides have repeatedly blamed each other for the shelling of the plant in recent weeks. The fighting has reached the point that the Red Cross issued an appeal urging all sides to refrain from fighting near a nuclear power plant. "Fighting should not happen in, around, to and from a facility like Zaporizhzhya. We know what the consquences are," said organization head Robert Mardini on a trip to Kiev, noting that it would be impossible to provide aid in a nuclear disaster zone. Meanwhile, Russia launched a large military manoeuvre on Thursday with more than 50,000 soldiers, even as its war with neighbouring Ukraine continues. The exercise is due to last almost a week and is being conducted in the east, thousands of kilometres from the front line of fighting in Ukraine. Russia's Defence Ministry said countries including China, India and Mongolia were taking part, alongside several ex-Soviet republics, including staunch Russian ally Belarus. It provides an opportunity for Moscow to demonstrate its close relations with other countries amid severe tensions with Western nations sparked by its invasion of Ukraine. The "Vostok 2022" (East 2022) exercise will see 5,000 military vehicles, 140 aircraft, 60 warships and other boats deployed, according to Moscow. The manoeuvre will take place at military training areas in eastern Siberia, the far east of Russia and in the Sea of Japan. The participation of China and India in particular is of interest to the West. Relations between the two most populous countries in the world are strained since a military incident on their joint border in the Himalayas two years ago which left several dead.