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EXHIBIT 12.1

Mexican GAAP

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

								Year ended Decemer 31
		June 2002		June 2001		December 2001
								2000		1999		1998		1997
		(thousands of pesos)
Mexican GAAP
Fixed Charges:
	Interest capitalized in fixed assets	2,645,509		2,004,202		3,779,541		3,913,180		5,119,428		3,329,393		2,282,605
	Interest in the specific reserve for exploration and depletion	99,644		443,632		86,553		814,739		864,553		803,361		752,237
	Interest expense	9,129,140		7,745,562		15,832,884		15,618,066		9,846,918		6,568,022		4,567,172
Total interest cost		11,874,293		10,193,396		19,698,978		20,345,985		15,830,899		10,700,776		7,602,014
Total Fixed Charges*		11,874,293		10,193,396		19,698,978		20,345,985		15,830,899		10,700,776		7,602,014
Earnings after IEPS taxes and Hydrocarbon Extraction duties		(6,361,349	)	(6,024,918	)	(34,090,587	)	(19,710,392	)	(21,156,771	)	(11,587,990	)	7,133,256
Fixed Charges:
	Interest cost net of amounts capitalized	9,129,140		7,745,562		15,832,884		15,618,066		9,846,918		6,568,022		4,567,172
Total Fixed Charges (net of amounts capitalized)		9,129,140		7,745,562		15,832,884		15,618,066		9,846,918		6,568,022		4,567,172
Earnings after taxes and duties plus fixed charges (net of amounts capitalized)		2,767,791		1,720,644		(18,257,703	)	(4,092,326	)	(11,309,853	)	(5,019,968	)	11,700,428
Ratio of earnings to fixed charges		—		—		—		—		—		—		1.54

*

This figure does not include rental expnese

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

								Year ended December 31
		June 2002		June 2001		December 2001
								2000		1999		1998		1997
		(thousands of pesos)
U.S. GAAP
Fixed Charges:
	Interest capitalized in fixed assets	3,223,160		2,309,296		5,112,410		4,273,611		5,713,187		4,412,094		3,061,280
	Interest expense	8,651,133		7,884,100		14,586,568		16,072,374		10,117,712		6,288,682		4,540,734
Total interest cost		11,874,293		10,193,396		19,698,978		20,345,985		15,830,899		10,700,776		7,602,014
Total Fixed Charges*		11,874,293		10,193,396		19,698,978		20,345,985		15,830,899		10,700,776		7,602,014
Income Earnings after taxes and duties		(4,799,754	)	(1,524,046	)	(25,444,111	)	(16,696,716	)	(15,370,295	)	(27,364,258	)	9,176,816
Fixed Charges:
	Interest cost net of amounts capitalized	8,651,133		7,884,100		14,586,568		16,072,374		10,117,712		6,288,682		4,540,734
Total Fixed Charges (net of amounts capitalized)		8,651,133		7,884,100		14,586,568		16,072,374		10,117,712		6,288,682		4,540,734
Earnings after taxes and duties plus fixed charges (net of amounts capitalized)		3,851,379		6,360,054		(10,857,543	)	(624,342	)	(5,252,583	)	(21,075,576	)	13,717,550
Ratio of earnings to fixed charges		—		—		—		—		—		—		1.80

*

These figures do not include rental expense

2

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EXHIBIT 12.1

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES