Mr Singh asked Ms Banerjee to take all possible steps so that peace is restored in the hill station where people are protesting against "imposition" of Bengali in schools by making the language mandatory.
The Gorkha Janmukti Morcha, which is in power in the semi-autonomous Gorkhaland Territorial Administration, has started an agitation demanding a separate state -- Gorkhaland.
In Kolkata, Ms Banerjee said, "What is happening today is a deep-rooted conspiracy. So many bombs and arms cannot be gathered in a day."
"I am ready to sacrifice my life, but I will not allow Bengal to be divided," she told reporters.
"There is a terrorist brain behind this hooliganism. We have got clues that they have connections with underground insurgent groups in the Northeast. There are some other countries also helping," Ms Banerjee said.
Army contingents were deployed to control the situation and they staged flag marches in several areas of the violence-hit hill district, where the indefinite shutdown to press for a separate Gorkhaland entered the third day.
The home ministry had yesterday put on hold sending additional paramilitary personnel to Darjeeling as no report on the ground situation had come from the West Bengal government.