SAO PAULO, Brazil - Brazil's Supreme Court is set to decide if scientists in Latin America's largest country can conduct embryonic stem cell research, which many say can lead to cures for degenerative diseases such as Parkinson's and Alzheimer's.

The court's 11 justices are scheduled to rule Wednesday on a 2005 petition by then-Attorney General Claudio Fontelles, who argued that a new law allowing embryonic stem cell research was unconstitutional because it violates the right to life.

The law opened the way for research with embryos resulting from in-vitro fertilization that are frozen for at least three years.

"Brazil has the potential to be a significant leader in this field," said Bernard Siegel, the executive director of the Florida-based Genetic Policy Institute. "And if the Supreme Court decides to allow this kind of research, then Brazil will become the Latin American leader in this field."

He said Brazilian scientists have done "pathfinding" work with adult stem cells for the treatment of cardiovascular diseases and Type 1 diabetes. If given the green light to use embryonic stem cells, "then there is no reason why they won't be able to make important breakthroughs," he added.

Roman Catholic Church officials have urged the court to ban such research because the process results in the destruction of embryos, which it and other groups say ends human life.

"Our position is not against science," Archbishop Geraldo Lyrio Rocha, president of the National Conference of Brazilian Bishops, said last week. "It is in favor of life."

He noted that the church supports adult stem cell research, which he described as "ethically acceptable."

Adult stem cells, which are harvested without destroying an embryo, can be used to recuperate damaged tissue. But scientists say they are less flexible than embryonic stem cells, which can develop into different types of cells.

"Adult stem cells are excellent and have generated a lot of valuable knowledge," said Mayana Katz, a University of Sao Paulo geneticist. "But embryonic stem cells are more powerful and offer many more possibilities to find cures for diseases like Parkinson's and Alzheimer's."

She said that while embryonic stem cell research is legal, scientists have put most projects on the back burner pending the Supreme Court's ruling.

"We want the chance of conducting the kind of research being done in developed countries like Great Britain, Sweden, Japan and Israel," she added.

Meanwhile, a January survey conducted by the Public Opinion Research Institute, or Ibope, shows that 95 percent of those interviewed favor embryonic stem cell research.