Official sources said the Dr Singh had gone straight from the Parliament to the MP's residence to avoid inconvenience to the public, but while returning home, he found the gates of the Parliament House complex closed.
When officials checked with the Parliament security they were curtly told that since no information about the PM's movement was given to them in advance, the convoy could not be allowed to pass through, the sources said.
They said it is a standard practice to close all the gates of Parliament at 8 pm. The PM's security immediately took a different route to reach his 7, Race Course residence.
The incident was reported to the home ministry by the Delhi police, which did not like the way Dr Singh's motorcade was turned back from the gates of the Parliament, creating an alleged security risk to him, sources said.