Adds details from the memo halting litigation, paragraphs 2-3

By Sarah N. Lynch

WASHINGTON, Jan 24 (Reuters) - U.S. President Donald Trump's administration has halted all pending environmental litigation and reassigned four career Justice Department attorneys focused on environmental issues, according to three sources familiar with the matter and a pair of memos seen by Reuters on Friday.

The memos order the division not to file any new lawsuits or other legal briefs and to halt all pending settlements and consent decrees to give the new Republican administration time to reconsider previously agreed deals.

The change, one of the memos said, is meant to ensure the federal government "speaks with one voice in its view of the law and to ensure the president's appointees or designees have the opportunity to decide whether to initiate any new cases."

The decision to move the four officials, who are not political appointees, from overseeing the natural resources, environmental enforcement, appellate and environmental crimes sections is the latest in a string of similar actions as Trump shakes up the federal government's 2.2 million-strong workforce.

The department's Environment and Natural Resources Division is responsible for bringing criminal and civil cases related to air and water pollution, animal welfare and public safety, as well as defending in court government agencies such as the Department of the Interior and the Department of Energy.

The four section chiefs were told in an email late Thursday they have 15 days to accept the new assignment to a newly created Sanctuary City Working Group or face adverse consequences, the sources told Reuters.

A Justice Department spokesperson declined to comment.

The sources were granted anonymity because they are not authorized to speak to the media. The sources said the reassigned officials have not been provided further details about their new assignments.

Trump has long dismissed climate change as a "hoax," vowed to cut regulation and on his first day in office withdrew the U.S. from the Paris climate treaty.

Four other Justice Department employees who worked on environmental justice issues were also placed on paid administrative leave this week, four sources familiar with the matter said.

The four officials placed on leave include Cynthia Ferguson, who led the environmental justice office, and Lana Pettus, a prosecutor who worked on some high-profile cases such as the 2015 criminal Clean Water Act case against Duke Energy DUK.N.

The Trump administration this week ordered anyone in the federal government on diversity, equity and inclusion issues to be placed on leave, and also called for the elimination of any office or position involving environmental justice.

Ferguson and Pettus could not be immediately reached for comment.

The order to freeze all pending environmental regulation was issued to employees on Thursday morning, the sources said.

It is similar to another memo issued earlier in the week to the Civil Rights Division which also halted all litigation, including efforts to finalize court-approved settlements with Minneapolis and Louisville to address civil rights abuses by the police.

(Reporting by Sarah N. Lynch; Editing by Scott Malone and Marguerita Choy)

((sarah.n.lynch@thomsonreuters.com; 202-579-0289;))