Michael Eisele rallied fellow devotees in February, 2016 to stage the #FreeKesha demonstrations outside Sony Music's Big Apple headquarters, after the singer lost her court bid to cut ties with Luke's Kemosabe Records, a Sony subsidiary.

The ruling came as a huge blow for the Tik Tok star, as she had accused the hitmaker, real name Lukasz Gottwald, of sexually and emotionally abusing her during their 10-year working relationship.

Kesha has continued to pursue legal action against her longtime collaborator, with Luke filing a countersuit, and now documents obtained by Pitchfork.com reveal attorneys for the producer are seeking to summon Eisele to court for questioning.

In the legal papers, Luke's representatives claim Kesha and her team "closely coordinated" with Eisele, who also runs a fan account on Twitter, to spread "defamatory statements" online and "tarnish" the 43-year-old's reputation, in a bid to put pressure on Sony bosses to cut ties with the producer.

"As such, Plaintiffs believe that Mr. Eisele has information that is material and necessary to the prosecution of this action and is not reasonably available from any of the parties," Luke's attorneys explain.

Kesha's representatives have yet to comment on the report.

The warring parties, who have been locked in the legal battle since 2014, are scheduled to take part in a phone conference with a judge on 14 April (17).