Emergency services workers found another body Sunday at the Petroleos Mexicanos, or Pemex, headquarters in Mexico City, raising the death toll from last week's explosion at the complex to 34, the Office of the President said in a statement Sunday.

"I had an opportunity to walk around the disaster zone and can report that the body of one of the missing has been found," President Enrique Peña Nieto said.

Search teams found the body of Enrique Bartolome Hernandez Martinez, who worked for the company that provided maintenance services at the state-owned oil company's headquarters.

Peña Nieto toured the Pemex complex Saturday night and later met with his aides and armed forces representatives at the site.

Federal prosecutors are investigating the explosion along with army and navy experts, "but we cannot yet reach a conclusion at this time," the president said.

Government Secretary Miguel Angel Osorio Chong will discuss the investigation in a timely manner "once we have conclusions or information that allows us to reach a conclusion as to what the causes of this disaster were," Peña Nieto said.

Some 2,500 rescue workers - aided by specially trained dogs - are sifting through the rubble at the Pemex headquarters, which was torn by an last Thursday.

The explosion occurred in the basement of one of the complex's buildings.

The cause has not yet been determined and, according to official reports, investigators have not found indications of a fire, smoke nor an odor of flammable substances.

The main tower of the office complex, a 56-story structure, was not damaged in the blast. EFE