The US President is said to have told those close to him, including the head of the Environmental Protection Agency, that he will not honour the 2015 accord which seeks to cut global carbon emissions.
Having refused to bow to pressure from allies to back the landmark agreement, Mr Trump later tweeted: "I will make my final decision on the Paris Accord next week!"
Donald Trump tweeted that he would make a decision over the Paris Accord next week
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Donald Trump snubs G7 summit over climate change deal
But according to the Axios news agency, which cites three sources close to the talk, the President's mind is already made up.
A source who has been in contact with people involved in the decision told Reuters a couple of meetings were planned with chief executives of energy companies and big corporations and others about the climate agreement ahead of Trump's expected announcement later in the week.
It was unclear whether those meetings would still take place.
Trump has annoyed fellow G7 leader for fragging his heels over the Paris agreement
I will make my final decision on the Paris Accord next week!
Donald Trump's tweet on Saturday
The White House did not immediately respond to a request for comment.
The summit of G7 wealthy nations pitted Trump against the leaders of Britain, Germany, France, Italy, Canada and Japan on several issues, with European diplomats frustrated at having to revisit questions they had hoped were long settled.
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German Chancellor Angela Merkel voiced her frustration at Trump's lack of commitment to the accord
Mr Trump, who has previously called global warming a hoax, came under concerted pressure from the other leaders to stick to the Paris agreement, which was signed by 195 countries two years ago.
His apparent reluctance to embrace the first legally binding global climate deal clearly annoyed German Chancellor Angela Merkel, among others.
She told reporters: "The entire discussion about climate was very difficult, if not to say very dissatisfying.
"There are no indications whether the United States will stay in the Paris Agreement or not."