Thousands of Victoria Police officers are taking industrial action to try to slash state government revenue from high-yield speed cameras as part of a campaign for a pay rise. Nearly 18,000 officers across the state began the action at 7am on Sunday after 99 per cent of Police Association of Victoria members who participated in a recent ballot voted to take industrial action. The union and the police force have been locked in five months of negotiations over a new enterprise agreement for a four per cent pay rise and better working conditions, such as nine-hour shifts. The previous agreement expired on Thursday. Union secretary Wayne Gatt said the state's police officers were overworked and undervalued. "If the government wants to attack the bottom lines of my members' household, we'll attack theirs, by placing police cars beside the highest yielding speed cameras in the state to warn motorists to slow down before they are forced to contribute to the state's revenue," he said. "Members will also be telling the government and the community how they're feeling, by scrawling messages on police vehicle windows about the challenges of the job they do and why they deserve to be paid for it." Premier Jacinta Allan says the government won't intervene to break the deadlock between the union and Industrial Relations Victoria. "The government has made very clear to the people sitting around the table that we expect these negotiations to be conducted in good faith," she told reporters on Sunday. "Secondly, we want to see them concluded with a strong outcome." The union is planning 19 simultaneous actions by officers as part of the strike. Mr Gatt said officers aren't making unreasonable demands. "They deserve to be paid for the work they do and not be expected to work unpaid overtime every shift," he said. "They deserve the right to see their families more and to have enough money in their pockets to actually take care of them." Australian Associated Press