In the judgement this afternoon, Sir Robert Owen also agreed not to include any evidence questioning whether the UK authorities could have prevented Litvinenko's death.
The coroner admitted the exclusion of this evidence could result in the inquest becoming "incomplete, misleading and unfair" and took the unusual step of inviting the government to hear the secret evidence in a separate secret inquiry behind closed doors.
The inquest is scheduled to begin on 2nd October.
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In a wide-ranging Peston on Sunday interview, he said Parliament security needs reviewing and the PM's counter-terror strategy is flawed.
The terror attack carried out by Khalid Masood at Westminster that left four people dead lasted less than two minutes say police.
Two knives were found at the scene in Islington, North London, and the suspects fled on foot before being arrested.