A Washington University professor who claims he was "unfairly cut out" of a payments-company enterprise after developing key software is suing for fraud and patent infringement, The St. Louis Post-Dispatch reported.

Robert E. Morley, an associate professor of engineering, filed a lawsuit against Square and its co-founders Jack Dorsey and James McKelvey on Thursday, seeking unspecified damages. The St. Louis professor said he helped come up with the idea.

Square develops small plastic electronic devices that plugs into mobile devices, including smartphones and tablets and allows individuals and merchants to accept and process debit and credit card transactions.

"The business now known as Square was not created solely by Jack Dorsey and James McKelvey," said the complaint. "It was Professor Robert Morley - and Dr. Morley alone - who invented the Square card reader, and Dr. Morley co-invented the corresponding magnetic stripe."

A Square spokesman told Reuters the company plans on fighting the lawsuit.

"It's not surprising that Morley would file another desperate, baseless patent lawsuit given how poorly his initial claims have been received by the patent authorities," the spokesman said.

According to The St. Louis Post-Dispatch, Morley and the Square Company have a long-running dispute.

In 2010, McKelvey filed a lawsuit against Morley and his company, REM Holdings 3 LLC, saying that his name was left off a patent for the card reader device. That lawsuit is pending before the Patent and Trademark Office, Reuters reported.

In the new lawsuit, Morley alleges that he and the co-founders of Square formed a joint venture to "focus on a smartphone-payments business," but the two eventually ousted him from their plans and formed a new company.

Square was valued at $3.25 billion at its last funding around 2012 and may now be worth significantly more, Reuters reported.