The presidential candidate of the governing conservative National Action Party (PAN) on Friday said he wants an investigation into the possible provision of aid to the leftist front-runner by the government of Venezuelan President Hugo Chávez.

Felipe Calderón told supporters at a rally in the central state of Morelos that in recent days "evidence has emerged" of Venezuela´s support for the creation at public universities of cells backing the candidacy of former Mexico City Mayor Andrés Manuel López Obrador.

"This should be investigated and the full weight of the law should be brought to bear to prevent Hugo Chávez from actively interfering (and attempting to sway the outcome of the vote) in Mexico," Calderón said to supporters.

Mexico will hold elections on July 2 to choose a successor to President Vicente Fox - who is limited to a single six-year term - and fill 628 seats in Congress.

Five candidates are in the race to become the next chief executive, but only three are serious contenders: López Obrador, leading in the polls as the standard-bearer of a leftist coalition; followed in second place by Calderón; and in third by Roberto Madrazo, candidate of the once-dominant Institutional Revolutionary Party. (PRI)

The PRI has pluralities in both houses of Congress and controls a majority of state governorships, yet scandals have dimmed its hopes of regaining the presidency it lost to Fox in 2000 after 71 years in power.

While some Mexican analysts have said that Chávez - and even Cuba´s Fidel Castro - support the candidacy of López Obrador, seeing him as a potential ally, the former Mexico City mayor rejects comparisons to the Venezuelan firebrand.

The first sign of Chávez´s apparent support for the leftist came in 2004, when Venezuela´s then-ambassador to Mexico, Lino Martínez, unfavorably contrasted Fox´s performance as president with López Obrador´s management of the capital city.

Later, a Venezuela-Mexico diplomatic flap erupted last November over their differing views of the U.S.-proposed Free Trade Area of the Americas (FTAA), which resulted in the two nations´ recalling their respective ambassadors.

On that occasion, Chávez labeled Fox a "puppy dog of the (U.S.) empire" in response to Fox´s harsh rhetoric against opponents of the Washington-led FTAA trade initiative.