Matt Hancock is self-isolating after being alerted by the NHS Test and Trace app - and after being spotted in a busy park over the weekend.
The Health Secretary said he was alerted by the Test and Trace app last night, and will be staying indoors until Sunday.
The ten-day period suggests Mr Hancock was potentially exposed to the virus on Thursday or Friday, before he was spotted in the park.
In a tweet announcing the news, he added: "We all have a part to play in getting this virus under control."
In a video accompanying the tweet, he said: ""This self-isolation is perhaps the most important part of all the social distancing.
"I know from the app that I've been in close contact with someone who's tested positive, and this is how we break the chains of transmission."
The Health Secretary was spotted in a busy park over the weekend.
He was photographed strolling through Queen's Park in London wearing a shirt and jeans, which was teeming with parents and children, carrying a rugby ball and covered in mud.
A source said: "As you can see, Matt was outside for exercise."
Mr Hancock tested positive for Coronavirus in March, in the same week as Prime Minister Boris Johnson.
He said at the time that his symptoms were mild.
