US President Donald Trump's former national security adviser said on Friday that Twitter Inc had returned control of his personal account to him after it had been taken over by the White House, marking his first tweets since resigning in September."We have now liberated the Twitter account, previously suppressed unfairly in the aftermath of my resignation as National Security Advisor," John Bolton tweeted to his more than 790,000 followers. "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," he wrote.Bolton did not explain how the White House had blocked his access to the account, but asked in the post if it had been done "out of fear of what I may say?"A senior administration official told Reuters the White House did not block Bolton from accessing his personal Twitter account, "and wouldn't have the technical means to do so."Twitter did not immediately respond to a request for comment.Bolton is among various US officials described as being alarmed at Trump's controversial use of his personal lawyer Rudy Giuliani on Ukraine policy, which is under intense scrutiny as part of a Democratic-led impeachment inquiry.Former White House Russia expert Fiona Hill recalled in her testimony at public impeachment hearings on Thursday that Bolton had called Giuliani "a hand grenade who's going to blow everybody up."