Ethanol producer Manildra secured 20 meetings with NSW ministers and donated more than $160,000 to the Coalition in a ferocious lobbying effort before the introduction of new laws set to benefit the company, but which critics say will increase petrol prices by as much as 8 cents a litre.

Diary disclosures reveal Manildra representatives including chairman Dick Honan secured the meetings in the 15 months before cabinet backed changes to require small petrol retailers to sell an ethanol blend, E10, for the first time.

Premier Mike Baird and Energy Minister Anthony Roberts met with Manildra before last year's election. Credit:Edwina Pickles

They show Premier Mike Baird and Energy Minister Anthony Roberts met with Manildra on February 24 last year, shortly before the March 28 state election, after the company poured $35,000 into NSW Liberal Party coffers duringthe previous nine months.

Mr Roberts had four other meetings with Manildra before the election – one of which saw him take a tour of an ethanol plant – and one immediately afterwards.