SAO PAULO, Feb 13 (Reuters) - Brazil's largest independent rail company sees legal insecurity and the high cost of capital in the South American nation as hampering its ability to bolster infrastructure investments.

Joao de Abreu, chief executive of Rumo SA, said ideas floated by the government, such as reversing labor reform or rethinking the role of regulatory agencies, are detrimental to business.

"It is absolutely fundamental to keep the rules," he said at a business conference in Sao Paulo when asked by the host what the role of the state should be to attract private investments. "Instead of discussing reforms that were made, let us talk about what can be improved."

Abreu's remarks come as Brazil, an agriculture powerhouse, is poised to harvest another bumper grain crop and export larger volumes of staples like corn to its biggest customer, China.

He said the previous administration created a huge investment pipeline in Brazil, mainly in infrastructure.

However, companies here are paying interest rates of 15% or 16% per year to finance projects, which Abreu said is unsustainable beyond two or three years.

"The number-one concern is how Brazil will manage the fiscal part so that we have, at least in the medium term, a more palatable cost of capital."

Abreu also mentioned Brazil's rigid environmental rules as delaying projects.

He cited one recent example of an effort by the company to obtain an installation license to build a railway in Mato Grosso, in Brazil's farm country - a project that will consume 15 billion reais ($2.90 billion) in investments and generate 150,000 jobs.

"Four years to get a license," he said. "If you discuss how to reduce that to two years, you can get investments off the drawing board." ($1 = 5.1765 reais) (Reporting by Ana Mano in Sao Paulo Editing by Matthew Lewis)