MANILA, Philippines—Former National Economic Development Authority director general and University of the Philippines' economics professor Solita "Winnie" Monsod is to testify in a court hearing on Monday on charges of price manipulation against the Big Three oil companies.

Judge Silvino Pampilo Jr. of the Manila Regional Trial Court Branch 26 earlier subpoenaed Monsod, who is also one of the Inquirer’s columnists, to appear at the hearing on a motion for the issuance of a temporary restraining order and writ of preliminary injunction against the oil price hikes.

According to the judge, Monsod was invited as an amicus curiae or "friend of the court" and is expected to give her expert opinion on cartelization, monopoly and overpricing.

Last week, Energy Secretary Angelo Reyes also testified in court as an amicus curiae. During his testimony, Reyes disputed claims by former Neda director general Ralph Recto that the oil firms were engaged in price fixing and that petroleum products were overpriced by as much as P8.

Reyes cited the claims of current Neda acting director general Augusto Santos that Neda has no economic model or formula to determine what the pump prices should be.

Meanwhile, the dean of the School of Economics of the University of Asia and the Pacific, Peter Lee U, will be cross-examined on Wednesday by the lawyers' group Social Justice Society, which filed the case seeking to stop the oil price hikes.

During a hearing recently, U told the court that the oil prices and the profit of oil firms were reasonable and that there was no proof of cartelization.