JAKARTA (REUTERS) - The Indonesian president's drastic measures to control food prices by banning palm oil exports have helped lift his sagging approval ratings, an independent pollster said on Thursday (April 28).

President Joko Widodo has in the last week imposed an export ban that covers nearly all palm products, which are used in staples like cooking oil, saying people's need for affordable food trumped revenue.

The move boosted his rating four points to 64.1 per cent in an independent survey of about 1,200 people conducted from April 20 to April 25 - recovering slightly from when it slumped to 59.9 per cent earlier this week but still lower than the record high 75.3 per cent he enjoyed in January.

Burhanuddin Muhtadi, director at pollster Indikator Politik Indonesia, told a news conference the two main drivers of the uptick were the palm export ban and an ongoing graft probe into palm oil permits, which the Attorney General also announced last week.

"Why the approval rating increased is because the president's policy is in line with the public's popular preference," he said, adding that 66 per cent of respondents believed a palm export ban was needed to shore up domestic supplies.

Indonesia is the world's top producer and exporter of the edible oil. The export ban, which has shocked global markets and choked supply chains, has been enforced from April 28. It will last until cooking oil prices fall to 14,000 rupiah (S$1.34) per litre, said chief economic minister Airlangga Hartarto.

Security minister Mahfud MD told the same conference the latest survey showed the government had not lost the public's trust.