The head of the European Council on Thursday urged the United States president to not jeopardize climate change politics, ahead of a highly-anticipated announcement from the White House on the administration's stance on the Paris Accord to tackle global warming.

Donald Tusk waded into the uncertainty that has gripped global climate change policies since reports from Washington suggested he was planning to withdraw US backing from the Paris Accord that seeks to reduce global carbon emissions by the end of the century.

On his personal Twitter account, Tusk urged Trump not to endanger the global climate change initiative: "Please don't change the (political) climate for the worse."

Trump had earlier signaled, on the same social media platform, that he would announce his final decision on the Paris Accord during a statement at the White House Rose Garden at 3:00 pm local time (7:00 pm GMT).

Trump was the only G7 leader to not offer backing to the accord in a joint communiqué released at the end of a summit in Italy over the weekend, a move that concerned leaders of the European Union.

In the absence of immediate US support, China signaled its backing for the climate deal and vowed to reiterate its support jointly with the EU.

The head of the European Commission, Jean-Claude Juncker, and Tusk are both due to meet with China's prime minister Li Keqiang later in Brussels, ahead of a China-EU summit.

On Wednesday, Juncker directed a message toward Trump: "The Americans can't just leave the climate protection agreement. Mr Trump believes that because he doesn't get close enough to the dossiers to fully understand them."

"Not everything which is law and not everything in international agreements is fake news, and we have to comply with it," he added.