Mexico's IMSS social services agency marked the second anniversary of a fire at a daycare center that killed 49 children by insisting its nursery schools now operate under some of the world's "most rigorous" safety standards.

Though the investigation of the June 5, 2009, blaze at a daycare in Hermosillo, capital of the northern state of Sonora, has uncovered all kinds of irregularities, no one has yet been convicted.

The ABC daycare in Hermosillo was an IMSS facility, but managed by a private company under contract.

The IMSS said in a communique that after the tragedy in Sonora, "it has carried out rigorous inspections of its nursery schools, with criteria that comply with the highest safety and emergency-management standards."

Each one of the 1,451 IMSS daycares, "contracted out to provide the service and administrated directly," have been checked to make sure "they comply with the strictest national and international safety regulations," the note said.

As a result of these inspections, the IMSS has taken the decision to "cancel the contracts of 111 companies providing daycare services."

Press investigations have revealed that dozens of nursery schools in Mexico are operated by relatives of politicians - since they are a profitable business - and many operate without the slightest concern for safety.

Among the ABC's owners were the wives of two Sonora officials and a former finance chief of the Institutional Revolutionary Party, or PRI, the state's dominant political force.

Daycare centers in the IMSS system are only allowed to operate now if they have "an alarm system, smoke detectors, fire extinguishers, emergency lighting on evacuation routes and transit areas, proof of their employees' training, an emergency exit and an internal emergency-management program," to name just some of the requirements, the institution said.

The IMSS said it is currently possible for citizens to go on the Internet and review more than 10,400 documents with detailed data on nursery schools in Mexico.

Finally, the IMSS said that last month it took a survey among 12,117 households with children in their daycare centers, in which 94 percent of those polled considered that the nursery schools attended by their youngsters are safe.