BOGOTA, March 19 (Reuters) - Colombian President Gustavo Petro on Sunday said he had suspended a ceasefire with the Clan del Golfo, the country's largest criminal organization, because it had attacked police. Defense Minister Ivan Velasquez told reporters on Sunday night that the government had no doubt that the Clan was responsible for the violent act as well as a rifle attack against law enforcement, which Petro had referenced in a tweet earlier in the day. See here for a complete list of exchanges and delays