Thousands of teachers turned out for a march in Oaxaca city, the capital of the like-named southern Mexican state, at the start of a strike that is affecting 1.3 million students.

SNTE teachers union Local 22, which has 70,000 members, staged four marches Monday that coverged on the state capital's main square.

Union members plan to occupy the square until officials agree to their demands, union leaders said.

Teachers voted to go on an indefinite strike over the weekend because state officials have provided "minimal and insufficient" responses to their demands, union leader Azael Santiago Chepi said.

The union is not making any pay demands, focusing instead on educational and social issues, Chepi said.

Teachers want better uniform allowances for students, computers in all elementary schools and for the state to pay for the electricity used in schools, the union leader said, adding that parents currently pay the utility bills.

Union members also want officials to find Carlos Rene Roman, a teacher who disappeared on March 14, Chepi said.

The state government, which is led by Gov. Gabino Cue, is offering a reward of 500,000 pesos (some $43,500) for information about the whereabouts of the missing teacher.

Teachers should "think about the future of Oaxaca's children" and make the "strike as brief as possible," Cue, who took office last December after 82 years of Institutional Revolutionary Party, or PRI, rule in the state, said.

Oaxaca's government has offered 1.5 billion pesos (about $128 million) to end the labor dispute, all the money the state can afford, Cue said.

Union leaders, however, questioned the figures provided by Cue.

The governor offered only between 600 million and 700 million pesos ($51 million and $59 million), Chepi said.

Teachers should return to the bargaining table to seek solutions that are "solid, peaceful and favorable to education," Cue said.

About 70,000 teachers walked off the job in Oaxaca in May 2006, setting off a long conflict.

The labor dispute's transformation into a movement to oust former Gov. Ulises Ruiz occurred on June 14, 2006, when police used force to break up a sit-in by strikers in Oaxaca city's main square.

The clash lasted nearly four hours and left dozens injured and under arrest.

The incident marked the start of a six-month conflict in Oaxaca that left at least 20 dead, including an independent U.S. journalist, and millions in economic losses.

The protests were joined by the Popular Assembly of the People of Oaxaca, or APPO, which was created in June 2006 to support the teachers.

Former Gov. Ruiz was a polarizing figure even before the conflict with the teachers, as many accused him of rigging the 2004 election that brought him to power in Oaxaca.

The uprising against the governor was crushed by thousands of federal police and troops in November 2006, but not before at least 20 people - mostly Ruiz opponents - had been killed and the protests had caused millions of dollars in losses in the normally popular tourist destination of Oaxaca city.

Oaxaca is one of Mexico's poorest states and is also the one with the largest Indian population, in terms both of absolute numbers and as a proportion of the total inhabitants.