Whenever the Agency determines that a public notice should be issued under this Title, the Agency has the authority to issue an information demand letter to the owner or operator of the site or facility where the release occurred or is suspected to have occurred that requires the owner or operator to provide the Agency with the information necessary, to the extent practicable, to give the notices required under Section 25d-3 of this Title. In the case of a release or suspected release from an underground storage tank subject to Title XVI of this Act, the Agency has the authority to issue such a letter to the owner or operator of the underground storage tank. Within 30 days after the issuance of a letter under this Section, or within a greater period specified by the Agency, the person who receives the letter shall provide the Agency with the required information. Any person who, without sufficient cause, willfully violates, or fails or refuses to comply with, any letter issued under this Section is in violation of this Act.