Washington (CNN) Energy Secretary Rick Perry "supported and encouraged" President Donald Trump in July to speak to the newly-elected Ukrainian President, but on energy matters, the Energy Department said Sunday.

Energy issues were not discussed during the July 25 phone conversation between Trump and Ukrainian President Volodymyr Zelensky, according to a rough transcript of the call released by the White House. That call has become a key focus of House Democrats' impeachment inquiry into Trump.

"Secretary Perry absolutely supported and encouraged the President to speak to the new President of Ukraine to discuss matters related to their energy security and economic development. He continues to believe that there is significant need for improved regional energy security -- which is exactly why he is heading to Lithuania tonight to meet with nearly two dozen European energy leaders (including Ukraine) on these issues," Energy Department spokeswoman Shaylyn Hynes said in a statement.

The White House-released transcript of the call revealed Trump asked his Ukrainian counterpart to investigate Joe Biden and the activities of the former vice president's son, Hunter, who had been on a board of a Ukrainian natural gas company.

There is no evidence of wrongdoing by either Joe or Hunter Biden.