By Alexandra Alper and David Alire Garcia
MEXICO CITY, Feb 19 (Reuters) - The keenly awaited fine print that will flesh out a landmark Mexican energy reform will not require state oil giant Pemex to take minimum stakes in contracts and will set out national sourcing requirements, leading lawmakers said on Wednesday.
Mexico's Congress in December approved the reform that ends Pemex's 75-year monopoly on crude production and aims to attract significant new streams of private investment into the country's lumbering oil, gas and electricity sectors.
"Pemex will participate (in future exploration and production contracts) if it wants to participate," said Marco Antonio Bernal, who heads the energy committee in the lower chamber of Congress and belongs to President Enrique Pena Nieto's ruling Institutional Revolutionary Party.
"We're not interested in obligating anyone," he added.
Pemex executives have said privately that they firmly oppose such a requirement.
Signed into law late last year by Pena Nieto, the energy reform allows for new contractual options for Pemex as well as foreign or private oil companies, including production-sharing contracts and licenses.
The lawmakers also said that the secondary legislation will spell out national content requirements for the contracts, but said that the still undefined mechanisms will vary.
"It will depend on the field," said Juan Bueno, a federal lawmaker in the lower chamber of Congress and an energy specialist with the conservative National Action Party, or PAN.
He added that national content requirements for deep water developments may be zero while they would be higher for contracts in mature fields in which Mexican oilfield service companies have a much larger presence.
The key portions of the energy reform fine print will be unveiled by the middle of March, both lawmakers said.
"We are designing a program so that by the first half of March we will have the first laws that will form the spinal column for everything else that follows," said Bueno.
Bueno said Mexico's hydrocarbons law, the laws governing Pemex and national electricity utility CFE, as well as two laws defining new responsibilities for the country's energy regulators, will all be presented by mid-March.
Part of a broader collection of more than 20 so-called secondary laws, the legislation is needed to implement the constitutional changes approved in December, and must be approved no later than April 20.
But Bueno said the law that sets new tax rates and royalty payments for the oil and gas sectors, including the new tax structure for both Pemex and private or foreign energy companies, will likely not be considered until September.