(Recasts, adds details on rig, background on Mexican deepwater
drilling; adds byline)

By Timothy Gardner

WASHINGTON (Reuters) - Mexico's state oil company
Pemex will delay its deepest-ever offshore well until next year
due to concerns about deepwater drilling in the wake of the BP
Plc oil spill, a top regulator said Thursday.

"We are more concerned about best practices in deepwater,"
Juan Carlos Zepeda, the head of Mexico's recently formed
National Hydrocarbons Commission (CNH), told reporters at an
energy conference.

Zepeda said Pemex would drill its Maximino well sometime
next year, but would not estimate when. It had been expected to
start during the fourth quarter of this year.

A Pemex official confirmed the delay of drilling
the well, to be the deepest ever attempted by the company,
citing a decision to try a less-challenging prospect first.

Pemex hopes its deepwater resources will someday reverse
Mexico's declining oil production. The deep waters of the Gulf
of Mexico, which have emerged as a major oil production source
for the United States, are largely unexplored in Mexican
territory.

Mexico believes billions of barrels of oil lie in the deep
waters of the Gulf, but exploration efforts are only beginning.
Pemex has drilled fewer than 20 deepwater wells so far. It has
made some modest natural gas and oil discoveries but has not
yet turned up any major deepwater finds.

Company officials say they have no plans to slow future
exploration despite safety concerns raised by the BP disaster.

NEW RIG

The hydrocarbons commission, set up under reforms to energy
legislation enacted in 2008, has gradually been asserting its
position as an independent regulatory body. Its power is
limited to making recommendations to the energy ministry.

Zepeda said the commission was considering recommending
enhanced safety rules for deepwater rigs similar to those the
United States has been considering in the wake of the spill.

He said CNH was considering requiring a "double key"
standard in which more than one person within Pemex would make
final decisions on drilling procedures such as declaring that
cementing on a well has been completed.

That would be a "core for an important transformation" in
deepwater drilling, Zepeda said.

Mexico has been waiting for the delivery of a new drilling
rig capable of operating in ultra-deep waters to test prospects
like Maximino near the U.S. border. The rig is due to arrive in
the fourth quarter of this year.

The rig, completed earlier this year in South Korea, is
owned by local Mexican company Grupo R.

However instead of starting with Maximino, Pemex has
decided to drill its Tulipau-1 prospect first to get familiar
with the equipment, the Pemex official explained.

In the United States, the April 20 explosion on the
Deepwater Horizon oil rig killed 11 workers and hurt the
billion-dollar fishing and tourism industries across five
states along the Gulf of Mexico.

The 9,600 foot (2,900 meter) Maximino well lies about 18.5
miles (30 km) from the U.S. border at sea.

Zepeda said the delay would "give us the correct timing for
finishing working with Pemex on their review of internal
regulation and, in case it's necessary on top of that, specific
regulation for exploration and production."
(Additional reporting by Robert Campbell in Mexico City;
Editing by David Gregorio)