On Monday, Russian media reported that all of the stations on the Moscow metro had been checked after receiving hoax bomb threats, as were more than 100 schools and nurseries, and 20 shopping centres. Some 10,000 people were reportedly evacuated.
It remains unclear who is behind the bomb threats, and the security and emergency services have remained largely silent on the issue.
Other major cities have also been targeted, but no bombs have been found so far.
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