May 29 (Reuters) - United Airlines and American

Airlines ( AAL ) may be fierce rivals in the U.S. market, but

they have agreed to jointly support Azul ( AZUL ) as the

Brazilian carrier filed for bankruptcy protection earlier this

week.

The move comes as the major U.S. airlines look to boost

connections in Latin America's largest country. American's

backing of Azul ( AZUL ) is notable given its own ties to its local rival

Gol, now emerging from its own Chapter 11

proceedings.

The U.S. companies are set to invest up to $300 million in

an equity offering to repay Azul's ( AZUL ) debtor-in-possession

financing when it emerges from bankruptcy, according to a

securities filing released by the Brazilian firm.

"They believe in the long-term viability of Azul ( AZUL ), in our

network strategy and in what we have built," Azul ( AZUL ) Chief

Executive John Rodgerson told Reuters. "Brazil is going to be

really important to United and American."

Both airlines are expected to have codeshare agreements with

Azul ( AZUL ) and be on the Brazilian airline's board of directors when

it emerges from Chapter 11.

Azul ( AZUL ) filed for bankruptcy protection in the United States on

Wednesday, following similar moves by Gol and LATAM Airlines

, after months trying to restructure mostly pandemic-era

debt.

Rodgerson noted that although both United and American have

"great franchises" in Latin America, their routes connect Brazil

to different U.S. cities.

While United flies from Sao Paulo to Chicago, Houston,

Newark and Washington, American's flights are bound to Dallas,

Miami and New York's JFK Airport.

United has been an Azul ( AZUL ) shareholder since 2015, when it

bought a stake in the firm as a strategy to catch up with U.S.

rivals with a firmer foothold in South America's biggest air

travel market at the time.

United's Chief Commercial Officer, Andrew Nocella, said in a

statement the fresh deal would be an opportunity to expand its

business with Azul ( AZUL ).

American is a long-time partner of Brazilian carrier Gol,

which holds around 30% of Brazil's domestic market share -

roughly level with Azul ( AZUL ).

While Gol focuses on big cities such as Sao Paulo, Rio de

Janeiro and Brasilia, Azul ( AZUL ) serves far more destinations.

American Airlines ( AAL ) Chief Strategy Officer Stephen Johnson

said in a statement that Gol remained a key partner, while

praising Azul's ( AZUL ) plans as "extremely positive for the Brazilian

aviation market."