Two Russian passenger planes carrying a total of more than 80 people have crashed within minutes of each other, prompting concerns of a possible terrorist attack.

The Interfax news agency quoted a Russian government source Wednesday as saying one of the two planes had sent a distress signal indicating a possible hijacking before crashing near the southern Russian city of Rostov-on-Don.

Citing an aviation source, Interfax also said the fact that the planes had taken off from the same airport and disappeared within minutes of each other suggests the event was a planned action.

President Vladimir Putin has ordered the nation's central intelligence agency, the Federal Security Service (FSB), to investigate the incident - an action that is generally only taken in extraordinary circumstances.

No survivors have been reported from the two crashes.

The incident comes just days before a presidential election in Chechnya, where Moscow has been fighting separatist rebels for a decade. Rebels launched a major raid in the local capital Grozny last week and have vowed further attacks.