"We have not found involvement of any external force so far, but the CBI is conducting inquiries into some cases and if there is something, it will definitely come out," Singh, who is heading a seven-member central team to the riot-hit districts said in Kokrajhar.
He said that there were certain elements and criminals into the arms trade and trans-border trafficking from Nepal to India and Bangladesh, "but connecting them is not reasonable."
Stating that there was malicious campaign by misinformed people from social media sites in Pakistan, Singh said the actual sources of photographs and messages uploaded to Facebook, You-tube and Twitter to fire the communal passion were being ascertained.
He said, "So far 310 web sites have been blocked and many more are on the anvil as they come to our notice."
Political statements, he said, might also ignite passion leading to violence and one had to be very careful about it.
The top priority in riot-hit areas was to bring the situation under control as soon as possible and rehabilitate the displaced people, he added.
On relief measures, Singh said, "There is no lacuna on the part of state or district administration and people are generally satisfied on whatever has been provided so far though in such a situation, there is bound to be some complaints from such a large number of refugees."
