The spokesman confirmed a report in the Valor Economico newspaper, which said Vale's stake in Log-in is worth about 217 million reais ($106 million) at current market prices.
Log-In operates coastal container ships and shipping services, a container port in Vitoria, Brazil, a fleet of trucks, and facilities to move containers between trucks, trains and ships.
While the sale is under consideration, no decision to sell the company has been made, Valor said.
Vale is in the middle of efforts to sell underperforming and "non-core" assets to finance a major expansion of its principal iron ore mining business. Iron ore is the main ingredient in steel.
The Rio de Janeiro-based company would be willing to sell the Log-In stake if a buyer agreed to maintain the company's long-term strategy, Valor said, quoting Humberto Freitas, Vale's director of logistics, prospecting and technology.
Log-In is one of Brazil's main domestic cargo carriers and provides key shipping links between some of the country's major cities. It was created in 2007 when Vale sold most of its container shipping unit to outside investors.
Log-In's competitors include Aliança, the Brazilian transport unit of Germany's Hamburg Sud Line, and the Mercosur Line, the South American costal shipping unit of Denmark's Maersk Line, the world's largest container shipping company.
In a separate transaction, Vale plans to sell a stake in VLI SA, a company that owns the miner's railways and principal ports, to a strategic partner, company officials said earlier this year. Vale's railways and ports are focused on bulk transport of iron-ore minerals and other commodities such as soybeans.
Vale preferred shares, the company's most-traded class of stock, rose 0.5 percent to 40.88 reais Thursday on São Paulo's BM&FBovespa exchange.
Log-In stock rose as much as 4.2 percent to 41.12 reais, its highest price in more than eight months in Sao Paulo.
The Bovespa index of the most-traded stocks on the BM&FBovespa fell 0.2 percent in late-morning trading. (Reuters)