MANILA - Ayala Corp., the Philippines' oldest conglomerate, said on Thursday it raised its stake in its water utility arm to 43.3% via a P3.5-billion ($75 million) deal with British firm United Utilities.

Ayala Corp. currently holds 31.7% stake in Manila Water Co.

The local conglomerate would buy United Utilities' 81.9 million common shares and economic interest in 2 billion preferred shares in Manila Water, Ayala Corp. said in a statement.

But United Utilities would retain voting rights in Manila Water via its 40% ownership of unlisted Philwater Holdings Company Inc., which holds the local utility's outstanding preferred shares. The British firm would also continue to provide technical services to Manila Water, the Ayala Corp statement said.

Manila Water holds the right to operate water and wastewater services in eastern Manila until 2037.

Shares of Ayala Corp. gained 2.5% on Thursday and Manila Water climbed 1.6%, outpacing the main index which edged up 0.9%.