Indian states on alert after al Qaeda announces India wing

India ordered several states on Thursday to be on increased alert after al Qaeda announced the formation of a wing of the militant group in India and its neighbourhood, a senior government official said.

In a video posted online, al Qaeda chief Ayman al Zawahri promised to spread Islamic rule and "raise the flag of jihad" across the "Indian subcontinent".

The government believes it is authentic and has warned local governments, said an official who attended a security briefing in which the video was discussed with the home (interior) minister.

"This matter has been taken very seriously," the official told Reuters. "An alert has been sounded."