Captain Peter Willcox was also charged with resisting the authorities, an administrative violation.
The 30 defendants are being held in pre-trial detention centres around Murmansk, and three defendants' requests for bail were rejected on Wednesday. Greenpeace lawyers have said they will file a case with the European Court of Human Rights over the conditions faced by their clients in detention.
The Investigative Committee's statement suggested the piracy charges may be cancelled and replaced with other criminal charges.
President Vladimir Putin previously said that the activists were "obviously" not pirates, but investigators nonetheless pressed ahead with piracy charges.
"Given the information gathered during the course of investigating this criminal case, the charge that has already been brought against everyone is expected to be changed," Markin said.
In previous cases, people convicted of selling poppy straw in Russia have been sentenced to five or more years in prison.
Greenpeace and other commentators criticised the possible narcotics charges as ridiculous.
"We can only assume the Russian authorities are referring to the medical supplies that our ships are obliged to carry under maritime law," Greenpeace said.
- Independent