BOGOTA, Jan 19 (Reuters) - Colombia's aviation regulator annulled a business merger process between Avianca and Viva airlines due to procedural irregularities, meaning it will restart it without the companies having to reapply, the aviation governing body announced on Thursday.

The merger request by the airlines was rejected in November by the aviation regulator on the grounds that it posed risks to competition in the sector and the welfare of consumers.

However, Avianca and Viva filed an appeal in November and proposed alternatives like yielding some routes and granting better landing and take-off schedules to competitors.

The aviation regulator admitted the existence of a "substantial irregularity within the administrative process" due to the fact that for the appeal it applied a procedure set forth in a law, ignoring a special rule regarding the protection of competition.

The director of the aviation regulator, Sergio Paris, said at a news conference on Thursday that the process will be restarted quickly for which a special team was formed and that the consumer will be protected as established in the current regulations.

There was no immediate statement from Avianca or Viva.

Viva is going through a financially challenging situation due to the impact of the COVID-19 pandemic, aggravated by the increase in fuel prices during 2022 and the devaluation of the Colombian peso.

Avianca, which completed its restructuring process at the end of 2021 and successfully emerged from Chapter 11 of the U.S. Bankruptcy Law, has more than 130 aircraft, 12,000 employees and one of the largest operations in Latin America.

Viva, which emerged as a low-cost airline with operations in Colombia and Peru, has a fleet of 23 aircraft and some 1,000 direct employees.

The two companies signed an agreement in April 2022 seeking to become part of the same group and unify their economic assets, maintaining their respective brands and strategies to strengthen the airlines after the crisis in the airline industry worldwide as a result of the COVID-19 pandemic. (Reporting by Luis Jaime Acosta; Writing by Steven Grattan Editing by Alistair Bell)