NAUCALPAN, MEXICO, NOV. 11 -- Widespread cynicism and a sparse voter turnout marked today's elections for mayors and a legislature in the state of Mexico.

The common message from voters and non-voters alike was distrust. Few of the dozens of people interviewed -- from the poor neighborhoods of Nezahualcoyotl to the well-to-do suburbs of Naucalpan -- said they believed the ruling Institutional Revolutionary Party would recognize opposition victories.

The two leading opposition parties accused the government of tampering with the vote. The ruling party, known by the Spanish acronym PRI, claimed victory in Naucalpan -- the nation's wealthiest municipality -- based on early, unofficial returns.

With 60 percent of the Naucalpan vote counted, the PRI candidate for municipal president, Mario Ruiz de Chavez, said: "The tendency is in favor of our party. The trend is unalterable."

The opposition National Action Party also claimed to be leading in the key municipality.

"If the PRI is claiming victory already, they are not very serious about change," said Diego Fernandez, a National Action spokesman. "The government has acted in a dirty and irresponsible manner."

The state vote is being viewed as a test of the government's commitment to fair elections prior to the 1991 national elections for the federal Chamber of Deputies and Senate.

Mexico, the country's richest and most populous state, surrounds the capital and houses 30 percent of the nation's industry.

Mexico was one of five states where the government recognized the victory of leftist leader Cuauhtemoc Cardenas in the 1988 presidential election, but many of those who voted for Cardenas say the election was stolen from him and either cast their ballots skeptically or stayed away from the polls today.

High absenteeism was expected to favor the PRI throughout the state. Observers predicted that the ruling party would win the state capital of Toluca and a majority of the 121 municipalities and 34 legislative seats. Only about 25 of the municipal races, including Naucalpan and Nezahualcoyotl, were considered truly competitive.

The government of President Carlos Salinas de Gortari has invested more than $92 million in public works projects in Mexico state over the last two years in order to win back support for the PRI. In the municipality of Chalco, a poor area where the government has installed electricity and waterworks for tens of thousands of homes, the program appeared to be paying off.

Several voters interviewed there said they had cast their ballots for Cardenas in 1988, but would support the PRI this time. While they believed that the government has been installing services precisely because it fears the strength of the opposition, they said that they would vote PRI now to ensure that projects get finished.