Retuers/Manila

Philippine President Benigno Aquino's performance ratings have plunged to their lowest ever, two independent pollsters said on Monday, as a perception grew that he is not serious enough in efforts to fight corruption.

Aquino, the son of an assassinated opponent of dictatorship and his wife, a democracy hero and former president, won the presidency in 2010 on a promise of good governance and fighting graft but has struggled to rid the country of its image as the most corrupt in Asia.

A survey by independent pollster Pulse Asia, taken last month, showed Aquino's approval rating dropped from 70% in March to 56%. His trust rating also fell from 69% to 53% in the same period.

Another survey, by Social Weather Stations, also done last month, showed Aquino's net satisfaction ratings dropped to 25% from 45% in March, the lowest in four years. His highest was 67% in August 2012.

Aquino is ineligible for re-election under the constitution but the prospects for his Liberal Party's candidate are likely to be damaged if his popularity is undermined in the run-up to a 2016 presidential election.

"This is the largest decline in both approval and trust and it's also his lowest performance thus far," Ana Maria Tabunda, Pulse Asia research director, said in a television interview.

People were disillusioned by widespread corruption in government, she said, adding that her poll was taken at the same time that the government arrested three senators on plunder charges for misuse of congressional funds and rising cost of rice and other food.

Tabunda said the survey was largely complete by the time the Supreme Court rejected an Aquino creation of discretionary funds, called a Disbursement Acceleration Program, which has become the administration's worst crisis in four years.

Edwin Lacierda, the president's spokesman, acknowledged a "dip in enthusiasm" but said he was not alarmed.

"These numbers can be considered par for the course or average for this period," he said. "A healthy majority has expressed trust and confidence in the president."