'The government has announced that petrol prices will rise tomorrow.'
'It has been announced by the government that petrol prices will rise tomorrow.'
'Petrol prices has been announced to be risen tomorrow.'
Is it correct? No.
Rover
'The government has announced that petrol prices will rise tomorrow.'
'It has been announced that petrol prices will rise tomorrow.'
'Petrol prices has been announced to be risen tomorrow.'
Is it correct?
'The government has announced that petrol prices will rise tomorrow.'
'It has been announced by the government that petrol prices will rise tomorrow.'
'Petrol prices has been announced to be risen tomorrow.'
Is it correct? No.
Rover
'Petrol prices have been announced to be risen tomorrow.' Is it ok?
So I don't know how to change it... I guess that something is wrong with this part: 'to be risen tomorrow.'
You already have a passive solution to the active sentence.
Another one beginning with 'Petrol prices' is going to sound contrived and unnatural.
Rover
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.