Obaidul Quader told reporters about the watch on Sunday after a meeting of the Awami League secretaries at the party president’s Dhanmondi political office in Dhaka.
He said, “They (BNP) are trying to make a conspiracy. The government and the party both have kept them (Khaleda and Tarique) and their activities under surveillance.”
With no official date for return, Khaleda went to the UK on Jul 15 for treatment of her eyes and legs.
Tarique, his wife Zubaida Rahman and daughter Zaima Rahman live in that house along with the wife and daughters of his late younger brother Arafat Rahman Coco.
Awami League leaders have said the BNP chief, while staying in London, is plotting to thwart the next general elections.
The BNP leaders, on the other hand, have alleged that the government is trying to smear Khaleda’s image with baseless conspiracy theory even though she is in London only for medical reasons.