South Africa has made progress in talks for a potential purchase of Embraer's C-390 Millennium, the Brazilian planemaker said on Wednesday, after showcasing the military cargo aircraft in the African nation for the second time.

Embraer voiced optimism about clinching a sale as South African authorities said they were advancing in the "necessary steps for the selection of the much needed" aircraft for its National Defense Force, according to a statement.

Embraer did not detail how many planes could be sold or how far along the process was.

Sao Paulo-traded Embraer shares rose more than 1% in morning trading, outperforming benchmark stock index Bovespa and extending their year-to-date gain to 125%, buoyed by positive demand for the firm's aircraft.

Santander analysts noted that the South African Air Force, "plagued by budget constraints," currently has six Lockheed Martin C-130s. It once had nine, but two have been written off due to accidents and another cannibalized for spare parts.

"If the country chooses to replace the entirety of its operational airlifter fleet, a potential South African order for C-390s could represent a $720 million addition to Embraer's backlog," the analysts led by Lucas Barbosa estimated.

A potential deal with South Africa would represent Embraer's first C-390 sale to an African country. The plane has so far been tapped by Brazil, Portugal, Hungary, the Czech Republic, Austria, the Netherlands and South Korea.

The multi-mission aircraft, which competes with Lockheed's C-130, "is perfectly suited to replace the legacy aircraft currently in service with South Africa," Embraer said.

The Brazilian company presented the C-390 to President Cyril Ramaphosa and Defense Minister Angie Motshekga at the Africa Aerospace and Defence exhibition held earlier this month at the Waterkloof Air Force Base, it said.

Brazil and South Africa are both members of the BRICS group of major emerging economies.