General Motors of Canada on Friday said it had signed an agreement with the Quebec government aimed at increasing to $C1.2 billion ($US811 million) from $C800 million the supply contracts it gives in Quebec, Reuters reported. Reuters said that GM's decision follows months of negotiations with public officials after the closure last year of the company's Camaro and Firebird plant in Ste-Therese, the only car plant that was left in the province.