BRASILIA, Feb. 27 (Xinhua) -- The Brazilian Supreme Court Judge decided Tuesday to extend an investigation into alleged acts of corruption involving Brazil's President Michel Temer for 60 days.

The investigation is looking into an approval by the federal government of a series of concessions to promote national and foreign investment in Brazil.

The police has voiced suspicions that the presidential decree, approving these measures, was designed to favor certain companies.

Besides Temer, the investigation is also looking into Rodrigo Rocha Loures, a former advisor of Temer, and entrepreneurs Antonio Celso Grecco and Ricardo Mesquita of port company Rodrimar.

Since this case began, Temer has denied any wrongdoing and said the measures had been finalized after a long negotiation between the government and the port sector.

The Supreme Court has received documents and recorded phone conversations involving Rocha Loures.

In one of the calls, Temer was allegedly recorded giving information to Rocha Loures about the decree, and Rocha Loures then transmitted it to Mesquita. But the president has categorically denied any knowledge of this.