HARTFORD, Conn. — Connecticut state agency heads have been told to make sure their employees use Bradley International Airport and the state’s other public airports for any air travel while on official state business to help ensure the success of new nonstop routes.

In a recent letter to top state officials, Department of Administrative Services Commissioner Melody Currey said Democratic Gov. Dannel P Malloy and the state’s Office of Policy and Management have directed agencies to use state-based public airports for all new travel arrangements moving forward, provided they’re more cost-effective.

“In order for the Aer Lingus service and all other nonstop routes at Bradley to be successful, and for Connecticut to continue to grow as a transportation hub for the region, it is critical that we support our airports and utilize their services to the greatest extent possible,” Currey said in the Oct. 3 letter. She wrote how the six-year-old Connecticut Airport Authority relies on “support and loyalty” from Connecticut passengers.

The quasi-public agency has been working to establish more nonstop routes at Bradley in Windsor Locks, including the reestablishment last year of trans-Atlantic service to Dublin, Ireland on Aer Lingus. Bradley is New England’s second-largest airport.

It’s unclear how many state employees have been flying in or out of out-of-state airports for state-related travel, especially considering the state’s budget challenges and pressure to cut costs.

Alisa Sisic, public information officer for the Connecticut Airport Authority, said her organization doesn’t know how often state employees use other airports. OPM officials also did not have the information, explaining how state travel expenses are broken down by in-state, or out-of-state, not by the kind of transportation used, such as air or rail.

“We just thought that it was important to ensure that state employees are prioritizing support of the state’s airports when traveling on state business,” Sisic said in an email.

In her letter, Currey notes how the airport authority has continued the practice of providing free parking to state employees on state business. She said that should be considered when agencies are comparing costs at other airports. Also, Currey said nonstop service available at another airport should not take priority over connecting service at Bradley, unless timing is crucial.

“It is critical that we utilize Bradley to the greatest extent practicable for state travel so that Bradley, and all Connecticut public airports, continue to thrive and airlines will continue launching new nonstop routes at our state’s premier international airport,” Currey wrote. Norwegian Air launched nonstop service between Bradley and Edinburgh, Scotland in June, marking the airport’s second trans-Atlantic non-stop flight. Spirit Airlines also announced in June it would run additional nonstop flights between Bradley and Florida cities.