All nine people on board and five people on the ground were killed, as the jet narrowly missed high-rise office buildings full of workers in an upscale business district.

'Blow to president'

"It's a strong blow for Calderon. They've amputated his right arm," said political scientist Agustin Basave at the capital's UNAM university.

Mourino was a key figure in Calderon's battle against powerful drug cartels [Reuters]
Officials showed reporters radar images of the plane's trajectory as it descended toward the international airport and said they had not found signs of a mid-air explosion or evidence the pilot made emergency calls.

But analysts said that even without evidence, many Mexicans would suspect foul play in a country where fear of being a drug gang target hangs heavy over government officials.

Luis Tellez, the transport and communications minister, said there would be a "meticulous" and "detailed" probe and it could be weeks before the cause of the crash was known.

"So far, we have not detected any indications that suggest a hypothesis other than that it was an accident," he said, adding that the plane was under armed guard before it took off from central Mexico.

More than 4,000 people have died in drug violence this year, mainly traffickers in turf wars, but hitmen have also murdered a string of police chiefs in recent months.