The arrest of the union leader at his fortified home and office complex in Ciudad Madero, an oil-producing center 300 miles northeast of Mexico City, surprised many Mexicans who follow politics closely.

Mr. Hernandez was arrested Tuesday in a military assault on his heavily fortified home in Ciudad Madero, an oil-producing center 300 miles northeast of Mexico City.

To prove the contrary, all one has to do is to look at the environmental catastrophe of Prudhoe Bay, the oil-producing center only 60 miles west of the Arctic National Wildlife Refuge.

Kirkuk, the northern oil-producing center, is fiercely disputed between Kurds and mostly Sunni Arabs.

Kurdish rebels said today that their forces, swelled by defectors from the Iraqi Army, had captured six towns in the northern part of the country and were advancing on the oil-producing center of Kirkuk.

A cousin, Hashim Hassan al-Majid, is the governor of Kirkuk, a northern oil-producing center.

Kirkuk, once a city of several hundred thousand, is a major Kurdish province capital and the main oil-producing center in northern Iraq.

The Iraqis later removed tens of thousands of Kurds from the area around Kirkuk, a vital oil-producing center, and resettled many cities with Arab Muslims and Christians.

A key dispute is over the status of Kirkuk, Iraq's principal oil-producing center, and several other cities that the Kurds want included in their autonomous region but which Baghdad asserts are cities that should stay under central Government administration.

After the discovery of petroleum in the area in 1906 the town grew into a major oil-producing centre.