Bosses at U.S. superstore Wal-Mart have denied allegations suggesting they have been purposefully stalling a federal lawsuit over Tracy Morgan's harrowing car crash.

The 30 Rock star is still struggling to bounce back from the fatal road accident which killed his friend James 'Jimmy MACk' MCNair and left him critically injured in June (14), when a limousine they were passengers in collided with a Wal-Mart truck driven by Kevin Roper in New Jersey.

Morgan, who has yet to return to work almost six months later, is suing company executives for negligence, but last month (Nov14), Roper - who is not named as a defendant - filed legal papers seeking to delay the lawsuit as his attorney, David Glassman, did not want accusations about his alleged actions to impact his ongoing criminal case relating to the crash.

Morgan's lawyers challenged the motion on Monday (01Dec14), blaming Wal-Mart chiefs for the move, insisting the request is just a tactic being used by the defendants to reportedly avoid disclosing their safety practices.

However, Wal-Mart officials have since dismissed the claims as false.

Roper, who was accused of being sleep deprived at the time of the collision, pleaded not guilty to one count of death by auto and four counts of assault by auto earlier this year (14).

Two other passengers in Morgan's car were also left seriously injured in the accident.