People connected with Donald Trump's administration and the US Congress tried to influence his former national security adviser's cooperation with the investigation into Russian election meddling, prosecutors said in a court filing made public on Thursday.
Michael Flynn provided a voicemail recording of one such communication, it said.
It did not identify who he was in touch nor did they describe the exact conversations, but they said the former US army general recounted multiple instances in which "he or his attorneys received communications from persons connected to the Administration or Congress that could have affected both his willingness to cooperate and the completeness of that cooperation."
Prosecutors say they were unaware of some of those instances, which took place before and after he pleaded guilty to lying to the FBI about his contacts during the presidential transition period in 2016 with the-then Russian ambassador to the United States, until Flynn told them about them.
They revealed details about Flynn's communications in a court filing aimed at showing the extent of his cooperation with special counsel Robert Mueller's investigation into ties between the Trump campaign and Russia.
Flynn, a vital witness in the probe, is awaiting sentencing.
Meanwhile, the judge in the case ordered that portions of Mr Mueller's report that relate to Flynn be unredacted and made public by the end of the month.
The order from US District Judge Emmet Sullivan is the first time a judge is known to have directed the Justice Department to make public any portion of the report that the agency had kept secret. It could set up a conflict with US attorney general William Barr, whose team spent weeks blacking out from the report grand jury information, details of ongoing investigations and other sensitive information.
A redacted version of Mr Mueller's report released last month said that the evidence did not establish a criminal conspiracy between Russia and the campaign.
It did not reach a conclusion on whether Mr Trump illegally obstructed justice, but he did examine nearly a dozen episodes for potential obstruction, including efforts by the president to discourage cooperation.
However, it does reveal that after Flynn began cooperating with the government, an unidentified Trump lawyer left a message with one of his attorneys.
They reminded them that the president still had warm feelings for Flynn. They also asked for a "heads-up" if Flynn knew damaging information about Mr Trump.
Judge Sullivan ordered prosecutors to give him a copy of the audio recording they reference in the court filing and to make public a transcript of that call. He also directed them to file publicly transcripts of any calls with Russian officials such as the ambassador, Sergey Kislyak.
Flynn was supposed to have been sentenced in December, with prosecutors saying he was so cooperative and helpful in their investigation that he was entitled to avoid prison.
But after a judge sharply criticised Flynn during his sentencing hearing, he asked for it to be postponed so that he could continue cooperating with prosecutors and reduce the likelihood of being sent to prison.
The document also details how Flynn assisted investigators as they looked into whether the Trump campaign conspired with the Kremlin to sway the outcome of the 2016 election.
Flynn described to investigators statements from senior campaign officials in 2016 about WikiLeaks — which received and published Democratic emails that were hacked by Russian intelligence officers "to which only a select few people were privy," prosecutors said. That includes conversations with senior campaign officials "during which the prospect of reaching out to the whistleblowing website was discussed."
Agencies contributed to this report