Brazil's President Luiz Inacio Lula da Silva on Monday inaugurated a long-awaited subway station at Rio's Ipanema beach that links to the neighborhood where most of the 2016 Summer Olympics will be held.

After languishing nearly 20 years for lack of funds, the Ipanema station boosts the city's two main subway lines that have also been growing slowly since 1970 and now cover 40 kilometers (25 miles) and carry more than half a million passengers a day.

Deemed insufficient for a city of 11 million, Rio's subway and public transport system is a key concern which the International Olympic Committee hopes will be resolved before the 2016 Games are held.

The new, 270-million-dollar "General Osorio" station was described as "the biggest urban cave in South America" by its master builder, Luiz Moreira.

"Fifty years ago, Rio was the picture of desolation and abandonment," Lula said at the station's official opening, as he showed off the gleaming new facility. It will be open to the public on Tuesday.

The president then got on the first subway bound for Maracana station, under the famous soccer stadium, that serves the southern subway line to the Barra de Tijuca neighborhood, site of many of the Olympic venues.