MEXICO CITY (Reuters) - Mexican President Felipe Calderon said on Friday the eastern state of Veracruz, which has been convulsed by a wave of killings, had been "left in the hands" of the violent Zetas drug cartel.

"I think Veracruz was left in the hands of the Zetas. I don't know if was involuntary ... I'd like to think so," Calderon said at a meeting in Mexico City with campaigners trying to end drug-related violence that has racked the country.

The president did not elaborate on who was to blame for the situation in Veracruz, a state on the Gulf of Mexico ruled by the main opposition Institutional Revolutionary Party (PRI).

Polls show the PRI is in pole position to oust Calderon's conservative National Action Party (PAN) in presidential elections in July, and the government's war on drug cartels has been a major source of friction between the main parties.

Since Calderon deployed the army to crack down on Mexico's powerful drug gangs soon after taking office in December 2006, criminal violence has spiraled in Mexico, killing more than 44,000 people and damaging support for his party.

However, the PAN has hit back, saying that the worst of the violence has been in states governed by the PRI, which dominated Mexico during 70 years of often corrupt rule until Calderon's party won a historic election in 2000.

With an eye on the July 1 presidential vote, the PAN has tried to reawaken memories of PRI corruption. The PRI has governed Veracruz since the party's inception.

A bloody turf war between the Zetas gang and their former employers, the Gulf Cartel, has ravaged Veracruz, where scores of homicides have been reported in the past month.

(Writing by Dave Graham; Editing by Eric Walsh)