WASHINGTON - Former national security adviser Michael Flynn pleaded guilty Friday to lying to the FBI about his contacts with Russian Ambassador Sergey Kislyak, an ominous sign for the White House, as Flynn is cooperating in the ongoing probe of possible coordination between the Trump campaign and the Kremlin to influence the 2016 election.

When he was forced out of the White House in February, officials said Flynn had misled the administration, including Vice President Pence, about his contacts with Kislyak. But court records and people familiar with the contacts indicated he was acting in consultation with senior Trump transition officials, including President Trump's son-in-law Jared Kushner, in his dealings with the diplomat.

Flynn's plea revealed that he was in touch with senior Trump transition officials before and after his communications with the ambassador.

The pre-inauguration communications with Kislyak involved efforts to undermine policy decisions being made by the Obama administration, on sanctions on Russia and a U.N. resolution on Israel - potential violations of the law.

Flynn said in a statement: "It has been extraordinarily painful to endure these many months of false accusations of 'treason' and other outrageous acts. Such false accusations are contrary to everything I have ever done and stood for. But I recognize that the actions I acknowledged in court today were wrong, and, through my faith in God, I am working to set things right.

"My guilty plea and agreement to cooperate with the Special Counsel's Office reflect a decision I made in the best interests of my family and of our country. I accept full responsibility for my actions."

Flynn admitted in his plea that he lied to the FBI about several conversations in December with Kislyak. In one, on Dec. 22, he contacted the Russian ambassador about the incoming administration's opposition to a U.N. resolution condemning Israeli settlements as illegal and requested that Russia vote against or delay it, court records say. The ambassador later called back and indicated Russia would not vote against it, the records say.

In another conversation, on Dec. 29, Flynn called the ambassador to ask Russia not escalate an ongoing feud over sanctions imposed by the Obama administration, court records say. The ambassador later called back and said Russia had chosen not to retaliate, the records say.

Flynn admitted as a part of his plea that when the FBI asked him on Jan. 24 - four days after Donald Trump was inaugurated - about his dealings with the Russians, he did not truthfully describe the interactions. But perhaps more interestingly, he said others in the transition knew what he was up to.

Flynn admitted that he called a senior transition official, whose name is not listed in court records, at the Mar-a-Lago resort on Dec. 29 "to discuss what, if anything, to communicate to the Russian ambassador about the U.S. Sanctions."

And when the ambassador later informed him Russia would not retaliate, Flynn again told senior members of the transition team, court records say.

The records say that a "very senior member of the Presidential Transition Team" directed Flynn to contact officials from foreign governments, including Russia, about the U.N. resolution on Israel.

That official is also not named, but people familiar with the matter said it refers to Kushner. According to one transition team official, Kushner told Flynn that blocking the resolution was a top priority of the president-elect.

Abbe Lowell, Kusher's attorney, declined to comment.

Flynn is the highest-profile Trump ally - and the first aide who worked in the White House - to face charges in special counsel Robert Mueller III's investigation.

Trump developed a close rapport with Flynn on the campaign trail, where the general delivered fiery denunciations of Hillary Clinton, including leading a "Lock her up!" chant at the Republican National Convention.

Outside the courthouse Friday, a small group of protesters shouted "Lock him up!"at Flynn as he left the building.