A Boston Big Dig construction firm claims the document released last week purporting to be a 1999 memo criticizing tunnel safety is actually a fake.

The document, dated May 17, 1999 and signed by safety official John J. Keaveney, alerts officials at the Modern Continental Construction Co. to  potentially disastrous structural flaws in an I-90 tunnel ceiling -- the same tunnel ceiling that partially collapsed earlier this summer and resulted in a motorist's death.

The construction company says they never received such a memo from Mr. Keaveney, a former employee, and says the recently released document is "fabricated."

"Modern Continental has conducted a full review of its files and has found no copy of the memo purportedly written by Mr. Keaveney," said company spokesperson Paul Andrew.

"Based on an extensive review of documents, including invoices for delivery of materials, commencement-of-work records and safety reports signed by Mr. Keaveney, Modern Continental believes the memo he allegedly prepared in May 1999 was fabricated."

According to Mr. Andrew, documents in the company's possession contradict many of the assertions made by Keaveney's alleged memo, such as that he saw water dripping out of drilled holes and observed bolts and tiebacks exposed to the elements. Andrew says documents show that drilling of the holes in question did not begin until several weeks after May 17, and shipments of bolts and tiebacks arrived much later.

Mr. Andrew also pointed out that Keaveney, who worked for the company at the time as a safety official, expressed none of the alleged memo's concerns in his subsequent weekly reports.

The company's statement comes more than a week after Mr. Keaveney released the alleged memo to the Boston Globe. In the document, addressed to a superior at Modern Continental Construction, Keaveney  writes that he was "gravely concerned about the method used to install the tunnel ceiling" and expressed dismay at that prospect "that any innocent State Worker or member of the public be seriously injured or worse killed."

ABC News attempted to reach Mr. Keaveney yesterday, but co-workers said he was unavailable for comment. In an interview published this morning by the Boston Globe, Keaveney adamantly defended the document's authenticity. 

Mr. Keaveney’s lawyer, Edward Boyle, told ABC News that the document "speaks for itself."

The July 10 disaster that saw 12 tons of concrete ceiling panels crush a car and kill a female passenger marks a  tragic low-point in the Big Dig's construction history. Planned in the 1980s to ease traffic congestion in the Boston area, the project, officially called the Central Artery/Tunnel Project, has drawn repeated criticism over rising costs and perceived structural flaws since construction began in 1991.