March 4 (Reuters) - Low-cost air carriers JetBlue Airways (JBLU.O), opens new tab and Spirit Airlines (SAVE.N), opens new tab canceled their $3.8-billion merger agreement on Monday, seeing no path forward after a U.S. judge blocked the deal in January on anti-competition concerns.

A successful deal would have created the fifth-largest carrier in the United States and helped Spirit ensure its survival, but the deal had been on the ropes ever since a Boston judge said it would harm consumers by reducing competition.

“With the ruling from the federal court and the Department of Justice’s continued opposition, the probability of getting the green light to move forward with the merger anytime soon is extremely low,” JetBlue CEO Joanna Geraghty told employees in an internal note seen by Reuters.