Investigators yesterday handed Khodorkovsky's father a summons for his son to come in for questioning in Moscow this Friday, said Open Russia, an opposition news website created by Khodorkovsky, publishing a scan of the document.
The statement by the powerful Investigative Committee said that Khodorkovsky was "charged" over the murder of a Siberian mayor in 1998 for which his former security chief is serving life in jail.
Khodorkovsky, formerly Russia's richest man, spent a decade in prison on charges of tax evasion, fraud and embezzlement, which he blames on a political vendetta by President Vladimir Putin.
"It's as if they don't know my address," Khodorkovsky tweeted, calling the summons "a sad attempt at changing the topic of debate" in Russia.
In a later tweet, he posted another letter from the Investigative Committee saying he will only be formally charged on Friday, suggesting the authorities had got ahead of themselves.
"They've remembered that they have to charge me first," he wrote.
It was not clear whether he would be charged with masterminding the murder or a lesser offence.
Asked why Putin pardoned the tycoon despite allegations of involvement in the mayor's murder, Kremlin spokesman Dmitry Peskov said today that at the time there was "some information" but investigators now have a more complete case.
"We did not have some of the information that we have now, which led to the actions being taken by the investigators," Peskov told journalists.
Khodorkovsky's associate, Alexei Pichugin, the former security chief of Yukos, was convicted of the murder in 2007 and given a life sentence.
Russian investigators in August called Khodorkovsky's elderly father in for questioning as a witness over the case.
