Mexico's Interior Minister and deputy attorney general have been killed after their plane crashed into evening rush hour traffic in Mexico City.

Juan Camilo Mourino, an ally of President Felipe Calderon, and Jose Luis Santiago Vasconelos were among seven people, including other government officials, killed when the government Learjet smashed into parked cars in the city's business district shortly after midnight GMT.

The cause of the accident, which also injured 40 people, was not clear although a civil aviation disaster expert told Reuters that sabotage could not be ruled out, along with other possible causes like engine failure.

President Calderon, who is waging a high-stakes war against Mexicos' powerful drug cartels, paid tribute to Mr Mourino, a close aide and friend who has worked with him for years.

"Mexico has lost a compatriot who worked for the service of his country," said the President in a televised speech..

"The federal government, under my charge, in coordination with the relevant institutions, will carry out all necessary investigations in order to check in depth what caused this tragedy," he said.

Mr Vasconcelos, the deputy attorney general was for years a key player for years in Mexicos' army-led war on drug cartels, was among other government officials who died in the crash.

More than 4,000 people have been killed this year, mainly drug traffickers but also police and soldiers, by drug gang hitmen lashing back at Mr Calderon's anti-cartel campaign and fighting new turf wars with each other.

Drug gangs appeared to take their feud with the government to a new level in September when a grenade was lobbed into a crowd of civilians celebrating a national holiday. Authorities are holding three men charged with carrying out the attack for the Gulf cartel's armed "Zetas" wing.

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