Canada's authorities are expected to announce they have foiled a plot to carry out a major terrorist attack, media reports say. The Canadian Broadcasting Corporation says the alleged plotters were arrested on Monday morning after being under surveillance for more than a year. It reports that the arrests took place in Ontario and Quebec. Police are due to give more details shortly. The plot was not linked to the Boston Marathon bombings, reports say. The investigation involved a cross-border co-operation involving America's FBI and the Department of Homeland Security, according to the CBC. The alleged targets were in Toronto and southern Ontario, an unnamed official was quoted as saying by the Toronto Star newspaper. The police are expected to hold a news conference at 13:30 local time (19:30 GMT). "I cannot confirm any details. These will be provided at the press conference," Royal Canadian Mounted Police (RMCP) spokesman David Fallf told the AFP news agency. The reported arrests come as Canadian lawmakers debate a proposal to strengthen the country's anti-terrorism measures. BBC News - Canada 'thwarts major terror plot'