Emirates has refused to accept an apology after Delta's CEO controversially suggested that there might be a link between Gulf-based air carriers and 9/11 terrorist attacks.

A controversial debate between U.S.-based air carriers and their Arabian counterparts about receiving government assistance has been going on since a few months, Agence France-Presse reported.

Since the Gulf carriers have been able to seize a sizable chunk of transcontinental travel and turn their airports into major hubs on the routes between the West, Asia and Australasia, the U.S. big three carriers --Delta, American and United -- are reportedly lobbying the U.S. government to slow the expansion of Gulf carriers into the U.S. market.

U.S. carriers claim that the "Gulf Three"- Etihad, Qatar, and Emirates- have not only been receiving billions of dollars in subsidies for decades, but that Etihad has been funded with new routes and aircrafts through government handouts. But the allegations have been rejected by the Gulf airlines, who in turn have pointed out that U.S.-based carriers benefited from government help in the aftermath of 9/11.

However, it all came to a head when Delta chief Richard Anderson was asked whether bankruptcy protection for U.S. airlines should be seen as government assistance, according to CNN Money.

"It's a great irony to have the UAE from the Arabian Peninsula talk about that, given the fact that our industry was really shocked by the terrorism of 9/11, which came from terrorists from the Arabian Peninsula, that caused us to go through a massive restructuring." Anderson told CNN's "Quest Means Business" on Monday.

But Delta said on Wednesday that Anderson "didn't mean to suggest the Gulf carriers or their governments are linked to the 9/11 terrorists. We apologize if anyone was offended."

He "was reacting to claims the Gulf carriers have been making that U.S. airlines received subsidies in the form of payments from the U.S. government after the 9/11 attacks and the bankruptcy proceedings that resulted," the carrier clarified.

However, Emirates rejected the Atlanta-based airline's apology on Thursday.

"Emirates rejects the apology issued by Delta Air Lines in response to comments made by its CEO... which intimated a link between the Gulf carriers and the 9/11 attacks," the Dubai-based carrier said.

"We believe that the statements made this week by Mr. Anderson were deliberately crafted and delivered for specific effect."

"This brings into question his credibility as a CEO of a U.S. public listed company, as well as the integrity of the submission which his airline has submitted to the U.S. authorities," it added.