* Petrobras sells bond in six parts, demand tops $50 billion
* Move helps Petrobras raise more than half 2013 funding needs
* Petrobras steps up borrowing to finance $237 bln capital plan
RIO DE JANEIRO/SAO PAULO, May 13 (Reuters) - Brazil's state-controlled oil firm Petroleo Brasileiro SA sold $11 billion of global debt on Monday in the largest-ever bond offering by a Latin American company.
The deal was split in six tranches comprised of fixed- and floating-rate debt with maturities ranging from three to 30 years, sources told Reuters and IFR, a Thomson Reuters unit that covers the capital markets. Investors placed bids topping $50 billion for the debt, a sign of strong appetite for high-rated emerging market companies, IFR said.
Petrobras obtained more than half of the $20 billion it intends to borrow this year to ensure investment in oil exploration and production despite sagging revenue. The oil giant is seeking to spend $237 billion through 2017 in what is considered the world's largest corporate investment plan by a single company.
The Rio de Janeiro-based company last sold debt on Feb. 1, 2012, when it raised $7 billion from offering bonds of four different maturities. The largest sale to date in the region had been Petroleos de Venezuela SA's $7.5 billion bond transaction in April 2007, according to Thomson Reuters data.
The cash comes as Petrobras is expected to participate in an auction of oil and natural gas rights in Brazil this week, the first conducted by the government in five years.
Sources familiar with the transaction told Reuters that $1.25 billion in three-year paper was sold at a yield of 2.144 percent, or 1.75 percentage point over comparable U.S. Treasuries. About $1 billion of three-year, floating-rate notes maturing May 2016 were sold at a yield equivalent to 1.62 point over the benchmark three-month Libor.
The company sold $2 billion of five-year, fixed-rate paper at a yield of 3.125 percent, or 230 basis points over comparable Treasuries. Also, $1.5 billion of five-year, floating-rate notes were sold at 214 basis points over Libor, the sources added.
Other parts included the sale of $3.5 billion in 10-year notes at a yield of 4.522 percent, or 260 basis points over comparable Treasuries, and $1.75 billion of 30-year bonds at a yield of 5.764 percent, or 265 basis points over Treasuries, the sources noted.
Petrobras is expected to increase the amount by 5 percent to Asian investors in an over-allotment sale later on Monday, the sources added.
The company hired the investment banking units of Bank of America Corp, Banco do Brasil SA, Citigroup Inc, HSBC Holdings Plc, Itaú Unibanco Holding SA , JPMorgan Chase & Co and Morgan Stanley & Co to handle the deal.