Durham Tees Valley airport have expressed their "acute disappointment" over their lack of funding from the Regional Growth Fund.
The airport were hoping for a £5.9m grant in support of its Southside development.
“The Airport has now been notified officially that the Regional Growth Fund bid for £5.9m in support of the Southside development was unsuccessful.
"The Directors expressed acute disappointment and will be seeking an explanation for the decision.
The Board also reaffirmed its commitment to pursuing the Southside scheme which is vital to providing sustainable aviation at the Airport.”