President Donald Trump is expected to issue a new round of pardons Friday for individuals convicted of federal emissions-related offenses as his administration continues rolling back environmental enforcement that it has characterized as excessive government regulation.

Trump was scheduled to meet Friday afternoon with advisers to review clemency recommendations. Sources told CBS News the proposed pardon list is expected to focus on convictions tied to the Clean Air Act.

"President Trump is the ultimate decider on any clemency related actions," a White House official said in a statement to CBS.

The anticipated pardons would build on the broader Trump administration effort to ease criminal enforcement of emissions violations involving diesel vehicles and other environmental regulations.

At the same time, Trump is weighing several high-profile clemency requests, including one from music producer Sean "Diddy" Combs, according to sources familiar with the discussions.

Sources told CBS that Trump has privately discussed whether to grant Combs a pardon, but had not reached a decision as of Friday morning. One source said neither Combs nor other celebrity cases were expected to be included in the recommendations presented by the White House pardon team.

Combs is serving a federal prison sentence of just over four years at Fort Dix, New Jersey, after being convicted last year on two counts of transportation to engage in prostitution. He was acquitted of the more serious charges of sex trafficking and racketeering conspiracy.

The New York Times reported in January that Combs had written to Trump seeking a pardon, although the president said at the time he was not considering the request.

Also seeking clemency is Grammy Award-winning rapper Prakazrel "Pras" Michel of the Fugees, who is serving a 14-year federal prison sentence after being convicted of conspiring with Malaysian financier Jho Low to conduct foreign lobbying campaigns aimed at influencing the U.S. government.

Federal prosecutors have accused Low of helping embezzle $4.5 billion from Malaysia's 1MDB sovereign wealth fund. According to CBS, Low is also pursuing a presidential pardon, though one source said Trump has not decided whether either man will receive clemency.

The expected Clean Air Act pardons follow several moves by the Trump administration to reduce environmental prosecutions.

Last year, Trump pardoned Wyoming mechanic Troy Lake, who had served seven months in prison for violating federal emissions laws after disabling pollution-control equipment on diesel engines.

"We think this type of case is an example of government overreach," attorney Stewart Cables told CBS Friday. "That's why we are trying to get these pardons."