MANILA — Energy Secretary Alfonso Cusi on Thursday apologized for successive brownouts in Luzon island this week, as he assured that the supply was back to "normal."

Rotational brownouts hit parts of Luzon beginning Monday, as the hot weather pushed demand for power while supply was affected by maintenance work and unscheduled outages at key power plants in Luzon and low gas pressure from the Malampaya gas field.

The outages began the same day Cusi led a meeting of ruling party PDP-Laban in Cebu, drawing criticism from party president Sen. Manny Pacquiao.

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"Normal na po ang supply ng kuryente for today. Ang supply po is more than sufficient to meet the projected demand today," Cusi said in a Palace press briefing.

(The power supply is normal for today. The supply is more than sufficient to meet the projected demand today.)

The projected demand for Thursday is at 10,300 megawatts, while the supply is at about 11,600 megawatts, he said.

"I apologize for the last 2 days na nagkaroon po ng rotating brownouts. Dahil po 'yon dahil sa sabay-sabay po na nagkaroon po ng breakdown ng 4 na plantang malalaki," said Cusi.

(I apologize for the last 2 days, when there were rotating brownouts. These were due to the simultaneous breakdown of 4 big plants.)

The 4 plants were capable of yielding about 2,000 megawatts.

He said he has ordered an investigation into possible collusion among power plants that could have brought down the supply.

"Pero habang hindi pa po natatapos ang imbestigasyon, hindi pa po tayo makakapagsabi kung ano ba talaga ang nangyari," said the energy chief.

(But until the investigation is not yet finished, we cannot say yet what really happened.)

Sen. Sherwin Gatchalian, head of the Senate energy committee, said Thursday he has called for an investigation into the rotational brownouts.