BUENOS AIRES (Reuters) - Low-cost airlines Flybondi and Jetsmart are targeting Brazil as a top flight destination in coming months, looking to expand routes as the market opens up, executives at both firms said.

"Is it true that Brazil's missing an ultra-low-cost airline? Probably," the chief executive of Chilean carrier Jetsmart, Estuardo Ortiz, told journalists on Thursday.

The firm, which currently operates nine routes in and out of Brazil, sees the country as an "instrumental" market to its operations, Ortiz said.

Argentine competitor Flybondi is also weighing route expansions to Brazil, CEO Mauricio Sana told Reuters in an interview on Wednesday.

Over the last few months, Argentina has signed a slew of so-called "open-skies" agreements with other nations, including Brazil.

The agreement with Brazil ramps up the number of permitted flight frequencies between the nations. With Chile and Uruguay, however, carriers from those nations can operate domestic flights in Argentina and vice versa.

"The agreement signed with Brazil is regarding frequencies... it still doesn't include domestic flights. But the (Argentine) government wants to allow it," a source at Flybondi said on the condition of anonymity.

A source at Argentina's transportation secretariat, also on the condition of anonymity, confirmed that it hoped such an agreement could be signed.

"(Brazil) has Gol and Azul, which aren't low-cost airlines," the Flybondi source said. "Rates are super high and it majorly lacks connectivity."

The source added that Flybondi was weighing the possibility of operating domestic flights in Brazil.

Jetsmart, meanwhile, is "just focusing on international flights for the moment," Ortiz said.

The executive also said that regulations in Brazil, such as strict consumer protections and a proposal to automatically include luggage in ticket costs, affected the "viability" of operating there, in addition to high jet fuel costs.