Panama's Supreme Court is opening a corruption investigation of former President Ricardo Martinelli

A person close to the high court says that nine judges voted unanimously Wednesday to appoint a special prosecutor to investigate Martinelli. The person insisted on speaking anonymously because the ruling hasn't been made public.

Martinelli has denied the charges and says he's the target of a smear campaign by his successor and former ally, President Juan Carlos Varela.

The supermarket tycoon traveled Wednesday to Guatemala to attend a session of the Central American parliament amid media speculation he would seek asylum.

The investigation centers on the testimony of a former aide who accused Martinelli of ordering him to sign an inflated $45 million contract to purchase food for a government-run social program.