Philippine lawmakers yesterday rejected the appointment of President Rodrigo Duterte's controversial pick for environment secretary, heiress-turned-missionary and activist Regina Lopez.

Ms Lopez shut down 22 of the country's 41 mines in February and cancelled dozens of contracts for undeveloped mines, driving nickel prices to a year's high.

The Philippines is the world's top supplier of nickel ore and main shipper to China, the biggest market for the industrial metal.

In her brief tenure as environment secretary, she campaigned hard against mining companies she believes had been sacking the environment and evicting communities to shore up their bottom lines. Last week, she also announced a ban on future open-pit mining projects.

She once pointedly told a ranking congressman with a mining interest during one of her confirmation hearings: "Your brother is killing the mountain."

The mining lobby had pushed back, accusing her of making "arbitrary" decisions and imposing "unreasonable demands".

Finance Secretary Carlos Dominguez also testified during the confirmation hearings, saying Ms Lopez failed to observe due process when she ordered to close mining operations.

Ms Lopez was appointed by Mr Duterte on June 30 last year. Congressional confirmations in the Philippines usually happen months after ministers start work.

The 15-member Commission on Appointments' decision is the second dismissal of a member of Mr Duterte's Cabinet. The same panel in March rejected Mr Perfecto Yasay as foreign minister for failing to declare his US citizenship.

Mr Duterte had initially expressed public support for Ms Lopez, but she has been seen as a polarising figure in the government.

In a statement yesterday, the President's spokesman praised her work but said that Mr Duterte has already begun looking for a replacement.

During a press conference after the ruling, Ms Lopez said those who voted against her nomination were "influenced by business interests".

"If the government co-opts to big businesses, then what hope does the poor have? What message are we giving here? If you wanna be confirmed, don't go against big businesses," she said.

Ms Lopez, 63, belongs to one of the Philippines' wealthiest families, with business concerns in media, property development and, ironically, mining. She has stayed away from the family business and, at one time, opted to do missionary work instead.