U.S. President Joe Biden's administration this week will release more policies it believes are needed to tackle climate change and is urging China to toughen one of its targets on greenhouse gas emissions, his top climate advisers have said.

Gina McCarthy, the White House's national climate adviser, did not say what policies would be released. A memo seen by Reuters on Thursday showed Biden will unveil a second round of executive orders as soon as Wednesday that include an omnibus order to combat climate change domestically and elevate the issue as a national security priority.

"We've already sent signals on the things that we don't like that we're going to roll back, but this week you're going to see us move forward with what's the vision of the future," McCarthy told a virtual meeting of the U.S. Conference of Mayors on Saturday.