The Lincolnshire Police are investigating the incident as an act of criminal damage, UK newspaper Express reported.
The law enforcement forces are viewing security tapes around the statue, whose cost is estimated at $339,000, the report said.
This is the third time the monument was defaced in Thatcher's hometown, according to the newspaper. The first incident took place in May, several hours after the statue was officially opened to public, when a man egged the statue, and the second occurred after a vandal spayed pink paint across the back of the sculpture.
This comes amid a political crisis in the UK, where a new prime minister will be announced today. On October 20, incumbent UK Prime Minister Liz Truss announced her resignation, less than two months after her appointment as leader of the Conservative Party and head of the UK government, becoming the shortest-serving prime minister in the UK history.