The official creditors committee in the Lehman Brothers bankruptcy fired the latest shot Tuesday afternoon in the dispute between Lehman and Barclays over whether Barclays received an improper “windfall” in its purchase of Lehman’s North American assets and liabilities last September, court records show.

The dispute has been brewing for months and has resulted in several motions for discovery and at least three lawsuits. In short: Lehman, its creditors and the trustee of its estate allege that certain higher-ups at both Lehman and Barclays arranged — without the knowledge of Lehman’s counsel at Weil, Gotshal & Manges — to sell most of Lehman’s North American assets to Barclays in late September 2008 under terms that were far too favorable to the buyer, according to court records and our prior reporting.