BOSTON (Reuters) - A former Akebia Therapeutics Inc (>> Akebia Therapeutics Inc) employee accused of insider trading was re-arrested on Friday after violating a bail condition as a prosecutor who once called him "increasingly unhinged" said he would seek the man's detention pending trial.

Schultz Chan, the former director of biostatistics at the Cambridge, Massachusetts-based biopharmaceutical company, had been free on $250,000 bond since his arrest last year on charges brought by federal prosecutors in Boston.

But a federal magistrate judge signed a new arrest warrant for Chan at a probation officer's request. While the reason was unclear, Chan's lawyer, Peter Horstmann, cited a condition that Chan report to his probation officer on Tuesday and Fridays.

"They can't abuse my civil rights like this," Chan told his lawyer before the court hearing began.

U.S. Magistrate Judge Donald Cabell, who signed the arrest warrant, had imposed that bail condition after prior issues with Chan reporting to his probation officer and warnings to the defendant against not complying with his conditions of release.

Cabell had been imposing increasingly tougher bail conditions beginning in July, when prosecutors said that Chan's wife had booked airline tickets for herself, Chan and their daughter to fly to China.

Chan, 54, is now expected to appear before Cabell again on Monday, at which point Assistant U.S. Attorney Stephen Frank said prosecutors would seek his detention pretrial.

At a hearing in July, Frank had said Chan "seems to be somewhat increasingly unhinged" and had been making threatening comments to the prosecution. Days later, Chan emailed another prosecutor to complain about "lies and frauds" in his case.

According to prosecutors, from 2013 to 2015, Chan engaged in an insider trading scheme with a friend at rival drug company Merrimack Pharmaceuticals Inc, Songjiang Wang.

Prosecutors said Wang tipped Chan ahead of announcements by Merrimack about clinical drug trial results, and Chan likewise supplied Wang information ahead of news of positive clinical study results for an Akebia drug.

An indictment said Chan also used inside information to trade himself in Akebia stock in 2015.

Both men have pleaded not guilty.

The case is U.S. v. Chan, U.S. District Court, District of Massachusetts, No. 16-cr-10268.

(Reporting by Nate Raymond in Boston; Editing by Lisa Shumaker)

By Nate Raymond

Stocks treated in this article : Akebia Therapeutics Inc, Merrimack Pharmaceuticals Inc