The Border Security Force (BSF) on Monday issued a "high alert" across all its formations along the 4,096-km India-Bangladesh border in the wake of the developments in the neighbouring country, officials said.

BSF director general (acting) Daljit Singh Chawdhary and other senior commanders have landed in Calcutta to review the security situation, they said.

The force has directed all its field commanders to be "on ground" and "deploy all personnel on border duty immediately", a senior officer told PTI.

The leaves of all the personnel posted along the Bangladesh border were cancelled in the last few weeks after Bangladesh witnessed massive protests and now all units have been asked to "acquire an all alert posture", he said.

The BSF guards the Indian front on the eastern flank of the country that runs along five states.

West Bengal shares a total of 2,217 kilometres of border with Bangladesh, along with Tripura (856 km), Meghalaya (443 km), Assam (262 km) and Mizoram (318 km).

Bangladesh Prime Minister Sheikh Hasina on Monday resigned and left the country, several news reports said, amid massive protests against her government that claimed more than 106 lives in the last two days.

However, there was no official confirmation about her quitting and leaving Dhaka.

Except for the headline, this story has not been edited by The Telegraph Online staff and has been published from a syndicated feed.