Trump has long complained about his attorney general’s decision to recuse himself from an investigation into Russian interference in the 2016 elections.
The US president has frequently suggested that by making the March 2017 decision to hand control of the probe by special counsel Robert Mueller to his deputy Rod Rosenstein, Sessions had failed to protect him.
In his latest remarks, which were recorded on Tuesday, Trump said what Sessions had done was “very unfair” and that he was “very disappointed” in him.
He also expanded his criticisms of him by suggesting that the attorney general, known to be extremely anti-immigrant, was not being tough enough of on immigration.
“I’m not happy at the border, I’m not happy with numerous things, not just this [the Russia investigation],” Trump said.
Analysts say the comments mean Trump is preparing to set out a case for firing Sessions.
The attorney general did not immediately respond to Trump’s latest attack on him.
In August he issued a rare statement when Trump accused him of failing to take control of the Justice Department, saying: “I took control of the Department of Justice the day I was sworn in.”
“While I am attorney general, the actions of the Department of Justice will not be improperly influenced by political considerations,” he added.