Air Canada announced Monday that it has suspended flights to Caracas effective immediately, citing concern about unrest in Venezuela.Air Canada posted the notice on its website Monday:Due to on-going civil unrest in Venezuela, Air Canada can no longer ensure the safety of its operation and has suspended flights to Caracas until further notice.The last flight departed Toronto on Saturday March 15 and Caracas on Sunday March 16, 2014.Flights will be resumed "once Air Canada is satisfied that the situation in Venezuela has stabilized." Until then, Air Canada is offering refunds for unused tickets to or from Caracas, and waiving change fees for those currently in transit.Air Canada typically operates three weekly flights between Toronto and Caracas.Anti-government demonstrations began in Venezuela in February, demanding an end to goods shortages, inflation, and high crime. Protesters have accused President Nciolas Maduro's government of responding violently to their opposition, with at least 20 killed during protests.