Canada’s federal police have opened a criminal investigation into a controversial plan to allow construction on greenbelt lands in Ontario, escalating a political scandal that has gripped the province and already forced a number of high-profile government resignations. The Royal Canadian Mounted Police announced on Tuesday that its sensitive and international investigations unit would investigate the C$8.3bn ($6.10bn) deal. The RCMP said in a statement it was looking into “allegations associated to the decision from the province of Ontario to open parts of the green belt for development”. Ontario premier Doug Ford’s office said it would “fully cooperate” with the investigation. It said: “We have zero tolerance for any wrongdoing and expect anyone involved in the decision-making about the greenbelt lands to have followed the letter of the law.” Ontario’s green belt, established in 2005, spans 2m acres (800,000 hectares) of farmland, forest, rivers and lakes around Toronto, and is meant to prevent unchecked urban sprawl and ensure protections for environmentally sensitive land. Earlier this year, Ford backtracked on promises not to develop the green belt, permitting development on 7,400 acres of environmentally sensitive land. At the time, his government previously justified the decision as part of a broader effort to address a mounting housing crisis in the province, promising to build at least 1.5m homes by 2031. In late September, however, Ford abruptly reversed course again after widespread public outrage, two damning watchdog reports and the resignation of two cabinet ministers. The RCMP investigation, which threatens to keep the issue at the forefront of the province’s politics, comes after Ontario’s independent integrity commissioner concluded that Ford’s housing minister had breached the law over the removal of lands. Ford also lost his minister of public and business service delivery when Kaleed Rasheed resigned after giving misleading statements to the integrity commissioner. An earlier, separate report from Ontario’s auditor general found that the government’s plan would benefit certain developers and landowners, adding C$8.3bn ($6.10bn) to the value of the properties. Earlier in the summer, the Ontario provincial police said it had received several requests from members of the public and advocacy groups to open a possible criminal investigation. But in late August, the police force said its anti-rackets branch would no longer be looking into the issue because of a “potential perceived conflict of interest”, and the matter had been referred to the RCMP. “While we recognize that this investigation is of significant interest to Canadians, the RCMP has a duty to protect the integrity of the investigations that it carries out, in order to ensure that the process leads to a fair and proper outcome,” the RCMP said Tuesday. “Therefore, no further updates will be provided at this time.”