MANILA -- Billionaire Enrique Razon offered to buy the rest of Manila Water, seeking to consolidate his control as the government renegotiates its contract to supply water to the capital's east zone, according to a stock exchange filing on Friday.

Razon's Prime Metroline Holdings set the tender offer at P13 per share, Manila Water said in a disclosure. On Tuesday, the port magnate got a 51-percent or majority voting interest after securing proxy rights from the water firm's parent, Ayala Corp.

The government is renegotiating its contracts with Manila Water and Maynilad Water Services Inc, which supplies the west half of the capital, after President Rodrigo Duterte tagged the concession agreements as "onerous."

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Shares of Manila Water fell 9 percent after the tender offer was announced. The P13 offer is lower than Manila Water closing price of P14.96 on Thursday.

After Duterte's tirades late last year, Manila Water dropped a P7.4-billion compensation claim which was awarded by a Singapore-based arbitration court over denied petitions for tariff hikes.

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-- with a report from Michelle Ong, ABS-CBN News