By Dave Graham

MEXICO CITY, Nov 23 (Reuters) - Legislation to implement a major overhaul of Mexico's telecommunications industry will not be approved until early next year, pushing back a deadline set for December, two senior lawmakers said on Saturday.

The secondary laws set out the fine print for a telecoms reform promulgated in June by President Enrique Pena Nieto which gives regulators sweeping powers to rein in billionaire Carlos Slim's telecoms giant America Movil and dominant broadcaster Televisa.

The bill raised hopes Pena Nieto was serious about breaking the hold a select few have on much of the economy, but a pile-up of pending bills in Congress has made the Dec. 9 deadline for the secondary telecoms legislation increasingly unlikely.

Federico Gonzalez Luna, a congressman who heads the radio and television committee in the lower house, told Reuters that to ensure the secondary laws were properly drawn up, they would now have to wait until 2014.

"There's no way of doing them earlier," said Gonzalez Luna, a member of the Green Party, allies of Pena Nieto's Institutional Revolutionary Party (PRI). "The plan is to get them done as quickly as possible, but to do them well."

Efforts would focus on getting the laws passed in the next period of Congress beginning in February, he added.

A delay in the secondary laws could give America Movil and Televisa more time to prepare their defense against steps by the new regulator to reduce their dominant positions in Mexico.

For now, Congress is scrambling to pass an energy bill put forward by the president in August to open up the state-controlled oil and gas industry to more private investment.

Fraught with political risks in a country where the 1938 nationalization of the oil industry was a defining moment, the energy bill is a central plank of Pena Nieto's economic agenda.

But the energy reform has been bogged down in the Senate, and the government is insistent it should pass this year.

To do that, the PRI must first push through an electoral reform to win the support of opposition conservatives it is banking on to provide votes for the new energy law.

The electoral reform is moving slowly in the Senate and PRI party chairman Cesar Camacho said on Friday a plan was under consideration to prolong Congress to make sure the energy bill is signed off by lawmakers this year.

ENERGY LAW BY CHRISTMAS?

Hector Gutierrez de la Garza, a PRI lawmaker who heads the communications committee in the lower house, said Congress would aim to approve the secondary telecoms laws early in 2014.