The UK PM aide Dominic Cummings was accused of violating the quarantine regime, the Associated Press reported.
Cummings, who lives in London, drove over 400 km to visit his parents in the city of Durham, located in the north-east of England.
Cummings, in turn, denies having committed any violation.
According to him, his wife had COVID-19 symptoms and he thought he was likely to also get sick, and relatives had offered to help look after their young son.
Earlier, UK media reported that Cummings traveled over 400 km to visit his parents, despite the ban imposed amid the COVID-19 pandemic. The incident occurred in late March or early April.
Opposition politicians demanded an explanation. There were also proposals to dismiss Cummings.