Former National Security Adviser John Bolton, whose name has repeatedly surfaced in impeachment hearings as a witness to key events, returned to Twitter on Friday and pointedly accused the White House of blocking access to his account after his resignation in September -- though President Trump denied involvement.

"[S]ince resigning as National Security Advisor, the @WhiteHouse refused to return access to my personal Twitter account. Out of fear of what I may say? To those who speculated I went into hiding, I’m sorry to disappoint!" he tweeted.

Bolton leveled the allegation after surfacing on Twitter earlier in the morning following his two-month hiatus from the platform, cryptically vowing to share the "backstory" of what happened to his account.

“Glad to be back on Twitter after more than two months. For the backstory, stay tuned….” Bolton had tweeted.

Bolton’s tweet appeared Friday amid a wide-ranging interview Trump gave on “Fox & Friends.” The president was asked whether he was involved in blocking Bolton’s Twitter account.

“No, of course not,” Trump said. “I had a good relationship with John.”

Later, Bolton tweeted again, adding: “We have now liberated the Twitter account, previously suppressed unfairly in the aftermath of my resignation as National Security Advisor. More to come…”

He also said, "In full disclosure, the @WhiteHouse never returned access to my Twitter account. Thank you to @twitter for standing by their community standards and rightfully returning control of my account."

The tweets from Bolton come after a packed week of hearings on Capitol Hill, where high-level current and former officials served as witnesses before the House Intelligence Committee as part of the impeachment inquiry against Trump.

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Bolton was invited by Democrats to appear for a deposition as part of the impeachment investigation earlier this month, but did not attend. Bolton was not under subpoena.

Witnesses, though, like former National Security Council official Dr. Fiona Hill, testified of Bolton's role during the lead-up to and aftermath of Trump’s now-infamous call with Ukrainian President Volodymyr Zelensky on July 25.

Hill, during her public hearing on Thursday, said that Bolton warned that Trump’s personal attorney Rudy Giuliani was a “hand grenade,” and said he would not take part in “whatever drug deal [Amb. Gordon] Sondland and [acting chief of staff Mick] Mulvaney are cooking up.”

Also, top U.S. diplomat in Ukraine Bill Taylor testified that Bolton warned against having the July 25 phone call between Trump and Zelensky.

"Ambassador Bolton was not interested in having--did not want to have the call because he thought it was going to be a disaster," Taylor said in his closed-door deposition last month. "He thought that there could be some talk of investigations, or worse, on the call."

"Turned out he was right," Taylor added.

At the center of the impeachment inquiry, which began in September, is Trump’s July 25 phone call with Kiev. That call prompted a whistleblower complaint to the intelligence community inspector general, and in turn, the impeachment inquiry in the House. Trump challenged the accuracy of the complaint, though the transcript released by the White House did support the core allegations that he pressed for politically related investigations.

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The president’s request came after millions in U.S. military aid to Ukraine had been frozen, which Democrats and witnesses have claimed shows a "quid pro quo" arrangement. Trump denies any wrongdoing. The aid was eventually delivered.

Bolton’s ouster came on Sept. 10, when the president tweeted that he had fired Bolton, saying he “disagreed strongly” with his suggestions on a range of issues.

“I informed John Bolton last night that his services are no longer needed at the White House,” Trump tweeted. “I disagreed strongly with many of his suggestions, as did others in the Administration, and therefore I asked John for his resignation, which was given to me this morning.”

But Bolton swiftly challenged Trump’s version of events, telling Fox News that he offered to resign, after he was sidelined from high-level discussions about military involvement in Afghanistan.

“I offered to resign last night,” Bolton told Fox News in a text message on Sept. 10. “There was no request for a resignation.”

A source, at the time, also told Fox News that Bolton sent his resignation letter earlier that day, prompting Trump’s tweet on Bolton’s removal.

Bolton later told Fox News that his "priority has always been policies that make America secure. Nothing more, nothing less."