The leader of Mexico's powerful SNTE teachers union was arrested for misappropriating union funds and will likely appear before a judge on Wednesday, Attorney General Jesus Murillo said.

Elba Esther Gordillo spent the night at the Santa Marta Acatitla prison on the outskirts of Mexico City following her arrest on Tuesday, Murillo said.

Gordillo allegedly engaged in financial transactions that used union funds to pay her personal expenses.

Investigators are still analyzing transactions in two of the 80 bank accounts targeted in the probe, Murillo said.

"These two accounts represent 75 percent of the economic universe being investigated. I believe they are the largest ones," Murillo told Televisa.

The accounts being investigated held 2.6 billion pesos ($204 million), the AG said.

The money, which came from the SNTE, was allegedly used to cover Gordillo's credit card bills, purchases at luxury stores, cosmetic surgery, real estate and other spending.

"The evidence is clear and solid," Murillo said.

Gordillo was arrested at the airport in Toluca, a city on the outskirts of the capital, because "it had been announced that she was going to hold a congress," the attorney general said.

"We had been watching the planes that arrived," Murillo said.

Televisa reported that the powerful union boss arrived in Mexico from San Diego, California, where she owns property.

The SNTE is the largest union in Latin America and Gordillo is considered Mexico's most powerful woman.

The union boss has the backing of the New Alliance Party, or PANAL, which holds 10 seats in Congress. EFE