The Homes Under the Hammer presenter posted from his hospital room on Thursday to tell fans that he had been rushed into emergency heart surgery on Wednesday night with massive amounts of fluid on his heart.
Now, Roberts, 58, has told The Sun that he could still be looking at a long period of recovery before he can go back home.
He said on Friday evening: "I’m being transferred to the respiratory team today as they think it might have started with a serious lung infection. I may be in hospital for another two weeks."
Thanking fans for their support, he added: "The heart problem seems to have stabilised.They are now running tests to find out what caused the problem in the first place. Seems this fluid build-up around the heart that nearly killed me was an effect (a deadly one) rather than a cause."
When he told fans about his health woes, Roberts posted a video of his hospital room on Instagram and said: "Well, I have to say this isn’t where I expected to be watching Homes Under the Hammer today.
"Bit of good news, bit of bad news. I ended up in the Royal United Hospital in Bath yesterday. I’ve been having quite a few chest pains and just feeling generally lousy.
"So I was brought in here and turns out I had a massive amount of fluid all around my heart, which was actually stopping my heart working.
"Had they not got rid of it, which they did in an emergency operation last night, then it’s sort of quite serious, like, hours to live kind of c***."
The TV star added that there were "lots of other complications" but said that he was thankful for his treatment.
Recently, Roberts impressed fans by driving a van load of supplies for people fleeing the war in Ukraine all the way to the Poland-Ukraine border after talking about how much he wanted to help.
Watch: Martin Roberts shares video after having emergency heart surgery