VLADIVOSTOK, Russia (AFP) - At least four people died and 49 were missing and feared dead Sunday after an oil rig capsized and sank in icy seas in far east Russia, the country's second major water disaster since July. Another 14 people were rescued as some officials clung to hope that more crew members could be pulled out alive even after spending some 16 hours in the frigid waters of the Okhotsk Sea. The Kolskaya oil rig platform with 67 people on board was being towed from the Kamchatka peninsula across the sea towards Sakhalin island when it got caught up in a storm, capsized and sank within 20 minutes, officials said. President Dmitry Medvedev ordered a probe into the disaster, telling officials to provide victims with all the necessary assistance. "This is a horrible tragedy which caught the crew off guard," said Dmitry Dmitriyenko, governor of the northern Murmansk region, which was home to 33 of the 67-strong crew. "I am asking you to believe in the rescue of the crew members, there is still a chance," Dmitriyenko said in a statement. The rescue operation was continuing through the night even though efforts have been hampered by strong winds and waves around five metres (15 feet) high. "The operation is taking place in complicated weather conditions," the Kremlin said in a statement. Rescue officials have repeatedly refused to say whether there was any hope of finding any more of the missing alive. They said wetsuits could protect people from frigid temperatures for around six hours. "It all depends on weather conditions," Anton Prokhorov, an official with the emergencies ministry in the city of Yuzhno-Sakhalinsk, told AFP. "People can stay alive in the water for around six hours... then hypothermia begins," he said, stressing however that instances had been recorded of people surviving in frigid water for longer than six hours. The federal sea and river agency said in a statement that the Kolskaya keeled over at 0145 GMT and sank within 20 minutes in water with a depth of over 1,000 metres. The crew was waiting to be evacuated by helicopter but the platform capsized and sank before they could board their rescue rafts, officials said. "The portholes were damaged by ice and waves, and water began going into the vessel," emergencies ministry spokesman Taimuraz Kasayev said. Officials blamed violations of safety rules for the disaster, a frequent cause of accidents in Russia. "The investigation is looking into safety regulation violations during the towing of the platform and a disregard of poor weather conditions as the main reasons for the incident, as there was a strong storm in the area," the Moscow-based Investigative Committee said in a statement. There was no immediate reaction from Prime Minister Vladimir Putin, who plans to reclaim his old Kremlin job in a March presidential poll. Another local emergencies ministry official, Elena Kim, said six aircraft and five vessels had been dispatched to the site of the disaster. She told AFP the commander of the crew had told everyone to put on wet suits but it was unclear whether everyone had the time to do so. Four people in wetsuits have been located in the water without any signs of life but rescuers were unable to pull them out because of the poor weather, the federal sea and river agency said in a statement. Emergencies officials said two of the 14 people rescued were suffering from hypothermia and another two had minor injuries. The rig was fully submerged by Sunday evening, and all four life rafts have been found with no one on board. Kasayev said the Kolskaya had experienced technical problems even before the accident, and had been forced to constantly pump water out of one of its air tanks due to a leak. The latest disaster comes after 122 people drowned in the Volga river in central Russia in July when an overcrowded pleasure boat sank in stormy weather. In August 2000, the Kursk submarine sunk in the Barents Sea with the loss of all 118 aboard. An inquiry found that a torpedo had exploded, detonating all the others. The catastrophe become a byword for Russia reluctance of the authorities to divulge information and was notorious for the slow reaction of then president Putin who stayed on holiday by the Black Sea. The Kolskaya rig belonged to state-owned company Arktikmorneftegazrazvedka (AMNGR) based in the northern city of Murmansk. It was engaged in shelf exploration in the Kamchatka peninsula for the Gazflot company, a subsidiary of Russia's gas giant Gazprom. The risk of an oil spill from the platform was minimal, officials said.