Petro's decision followed upset in Colombia's House of Representatives after a debate on the president's controversial health reform was abandoned after not reaching the necessary quorum. Some parties in the government's coalition threatened not to approve the original bill.

"The political coalition agreed as a majority has ended today due to decisions of some party presidents," Petro said in a message via Twitter late on Tuesday.

"Such a situation leads us to a rethinking of the government," he said in a subsequent Tweet.

The reshuffle could see the departure of some of Petro's 18 ministers, as well as movements of others to different portfolios, said one of the sources.

A number of Petro's ministers, including Minister of Mines and Energy Irene Velez, have faced harsh criticism since Petro took office nearly nine months ago on promises to make sweeping social and economic reforms.

Petro has largely backed his ministers, including Velez, though disagreement over the health reform proposal already lead to the exit of the education minister, Alejandro Gaviria.

Interior Minister Alfonso Prada could be take over as defense minister, said one government source who declined to be identified. Others, including Velez, could hold on to their posts, the source said.