Syndicates of Lloyd’s of London insurance market have filed a countersuit to Kanye West’s claim that he was owed $10m after canceling his tour last year, saying it found “substantial irregularities” in the rapper’s medical history.

The counterclaim was filed in federal court in Los Angeles on Tuesday and said West’s Very Good Touring Inc had failed to cooperate in the insurance company’s investigation into the claim for cancelled concerts, according to the court documents.

Lloyd’s said that its policies excluded any losses caused directly or indirectly by the possession or use of illegal drugs, the impact of prescription drugs not used as prescribed, or the use of alcohol.

The court documents said that in order to protect West “from public disclosure of details of his private life,” Lloyd’s would not include specific information it had obtained in relation to the claim. However, Lloyd’s said the underwriters’ investigation found “substantial irregularities in Mr West’s medical history”.

West, 40, sued Lloyd’s, an insurance market housing more than 80 syndicates in London, for nearly $10m in payouts after he cancelled his Saint Pablo tour in November 2016 with more than 20 shows left.

The musician’s lawsuit, filed in early August, said he was hospitalised with a “serious, debilitating medical condition”, following a week of no-shows, curtailed concerts and on-stage political rants.

West’s lawsuit said Lloyd’s had suggested “they may deny coverage of the claim on the unsupportable contention that use of marijuana by Kanye caused the medical condition”.

In its countersuit, Lloyd’s said West’s company and other representatives “have delayed, hindered, stalled and or refused to provide information both relevant and necessary for underwriters to complete their investigation of the claim”.

“Underwriters are informed and believe, and thereon these same persons have willfully concealed and or misrepresented relevant facts in an effort to thwart underwriters’ investigation,” the counterclaim added.

West’s lawyer, Howard King, said in a statement on Wednesday that Lloyd’s did not “want to honour a legitimate claim but can’t find a factual basis to deny a claim”.

Lloyd’s was seeking a jury trial. Representatives did not immediately return requests for comment.