More than 40,000 people were affected by the heavy rains that fell over the weekend in the Valley of Mexico and some southern states, the emergency management office said, adding that the downpours caused extensive damage.

Emergency management personnel are trying to confirm how many deaths occurred and assess the damage, agency spokesmen told Efe.

The areas most affected by the rain were the Valley of Mexico and the states of Oaxaca, Guerrero and Veracruz, the Social Development Secretariat said.

Disaster assistance teams have been sent to the affected areas, officials said.

The teams are working on clean-up, recovery and "safeguarding the physical integrity of the people" living in the areas, the secretariat said.

A state of alert was declared on Sunday in Mexico state, which surrounds the Federal District and forms part of the Mexico City metropolitan area, after a river overflowed its banks, flooding about 1,500 houses.

The National Water Commission, or Conagua, discontinued the alert on Monday, when the weather service forecast less precipitation in the Valley of Mexico over the next few days.

Water is being released from the dam system in the Valley of Mexico, especially Lake Guadalupe, La Concepcion and Angulo, to levels that will allow managers to deal with the rains expected over the next few days, Conagua chief Jose Luis Luege Tamargo said.

Workers are going to shift the flow of water from the Cuautitlan River so they can start repairing containment structures in the flood zone, the Conagua chief said.

At least 74 people have died since the rainy season started in June in Mexico, the emergency management office said.