Steve Bannon has been subpoenaed to testify before a grand jury in Mueller's Russia investigation

AP Photo/Evan Vucci, File

Steve Bannon.

• Special counsel Robert Mueller subpoenaed former White House chief strategist Steve Bannon to appear before a grand jury as part of the Russia investigation.
• News of the subpoena came on the same day that Bannon testified before the House Intelligence Committee about what he witnessed when he worked on the Trump campaign between August 2016 and November 2016.
• Bannon was a central figure in the latter part of the campaign and in the beginning months of the Trump presidency.

Former White House chief strategist Steve Bannon has been subpoenaed to appear before a grand jury in special counsel Robert Mueller's investigation into Russia's interference in the 2016 election, The New York Times reported on Tuesday.

News of the subpoena comes on the same day Bannon testified, in a closed-door hearing, before investigators on the House Intelligence Committee who are scrutinizing Russia's election meddling.

Bannon was one of President Donald Trump's top advisers during the transition period and in the White House. In addition to serving as chief strategist, he also had a seat on the National Security Council.

Rumors have swirled that Bannon, while in the White House, was responsible for some of the most damaging leaks about Trump's son-in-law, Jared Kushner - including one about Kushner's meeting in December 2016 with the CEO of a sanctioned Russian bank.

Bannon was also highly critical of a meeting Kushner, former campaign chairman Paul Manafort, and Trump's eldest son Donald Trump Jr. took with two Russian lobbyists in June 2016.

According to author Michael Wolff's book, "Fire & Fury: Inside the Trump White House," Bannon called the meeting "treasonous" and "unpatriotic."

"Even if you thought that this was not treasonous, or unpatriotic, or bad s---, and I happen to think it's all of that, you should have called the FBI immediately," Bannon added.

He later clarified that he was primarily criticizing Manafort, who he said should have known better than to meet with the Russians at the height of the campaign.

He also added that there was "zero" chance that Trump Jr. did not introduce the lobbyists to Trump.

Trump and his lawyers have denied any knowledge of the meeting. But the president attracted scrutiny last summer when The Washington Post reported that he "dictated" an initially misleading statement that Trump Jr. released in response to reports about the Trump Tower meeting.

The statement had to be amended several times after it emerged that Trump Jr. took the meeting after he was offered compromising information on then-Democratic candidate Hillary Clinton as "part of Russia and its government's support for Mr. Trump."

Bannon was also one of the officials Trump Jr. emailed about his repeated contacts with WikiLeaks in September 2016, according to documents obtained by The Atlantic.