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. Last Updated: 07/27/2016

British Investigators Return to London

LONDON -- British detectives investigating the death of former Federal Security Service agent Alexander Litvinenko returned to London on Wednesday after carrying out inquiries in Moscow, police said.

The team of nine officers said they had been offered "satisfactory" cooperation from Russian officials after arriving Dec. 4, a Scotland Yard spokeswoman said on condition of anonymity, in line with policy.

Litvinenko died Nov. 23 from poisoning by the radioactive isotope polonium-210 and inquiries into his death are being carried out in Britain, Germany, Russia, France and the United States.

"All nine of the officers have now returned to London and are following several lines of inquiry," said the spokeswoman. "They had satisfactory cooperation from the Russian prosecutor general's office."

Scotland Yard detectives were not allowed to question witnesses themselves during their Moscow visit but observed as Russian investigators conducted questioning.

Police officials confirmed that two Russian businessmen who met Litvinenko in a London hotel on Nov. 1 -- the day he fell ill -- had been questioned by the Russian and British investigators.

They are Dmitry Kovtun, who is undergoing treatment for radiation poisoning at a Moscow clinic, and Andrei Lugovoi, who formerly worked for a Kremlin bodyguard unit under the KGB.

The Prosecutor General's Office has opened a case of attempted murder in connection with Kovtun's poisoning.

In Germany, authorities have found traces of polonium-210 in several locations in Hamburg visited by Kovtun just before he flew to London for the Nov. 1 meeting.

German prosecutors are investigating whether Kovtun may have illegally handled radioactive material. But they have left open the question of whether the radioactive trail means he was involved in Litvinenko's poisoning.

Lugovoi, Kovtun and Vyacheslav Sokolenko, a third Russian businessman who was in London with them on the weekend of Nov. 1, have denied involvement in Litvinenko's death. All three met Litvinenko at London's Millennium Hotel, where three people -- two employees and a Swedish visitor -- have tested positive for polonium-210.

One staff member at the Sheraton Hotel was also exposed to the element, Britain's Health Protection Agency said.

London police officials could not comment Wednesday on the nature of the interviews with Kovtun and Lugovoi, nor on information collected during inquiries in Moscow.

On Tuesday, the Kremlin brushed aside claims that Scotland Yard investigators were unhappy about interference from Russians authorities. "British investigators were provided all opportunities to meet and to interrogate those witnesses whom they wanted to interrogate connected with this," Kremlin spokesman Dmitry Peskov said.