[Update 9:38 p.m. ET] The security issue was a bomb threat that had been called in at 10:43 a.m. (1:43 p.m. ET), Cpl. Sherrdean Turley of the Royal Canadian Mounted Police told reporters outside the airport.
[Update 8:28 p.m. ET] The plane, which was coming from Hong Kong, landed safely in Vancouver at 1:35 p.m. PT (4:35 p.m. ET), said Alisa Gloag, a spokeswoman for the Vancouver Airport Authority.
Passengers were deplaned and the aircraft was being towed to another area for inspection, said Gloag, who did not have information about how the threat was reported.
The Royal Canadian Mounted Police is investigating, Gloag said.
[Posted 8:09 p.m. ET] Two CF-18 Hornets were scrambled from a Canadian military base Saturday to escort a Cathay Pacific Airways flight into Vancouver's airport, according to an official with the North American Aerospace Defense Command.
The action was taken in response to a "potential threat" to the flight, Maj. Holly Apostoliuk of NORAD told CNN.
[Updated 6:41 p.m.] The case has rocked Mexico, with President Felipe Calderon saying he is closely monitoring the investigation into the disappearance of the former official, Diego Fernandez de Cevallos Ramos.
A statement on the Mexican president's website said that Calderon "from the first hours of the morning, has been in constant communication with the attorney general and with the secretaries of Interior and Public Security," about the investigation.
The statement said that Calderon has "communicated with one of the two children of Fernandez de Cevallos, who is facing this difficult situation with integrity, to offer his solidarity and the necessary backing to successfully locate Fernandez de Cevallos."
[Posted 5:12 p.m.] A former Mexican senator was reported missing on Saturday, Mexico's attorney general's office said.
The former official, Diego Fernandez de Cevallos Ramos, was last seen on the ranch of his home in Pedro Escobedo, in central Mexico's state of Queretaro, the country's official Notimex news agency reported.