By Elizabeth Piper and William James

LONDON (Reuters) -Britain's Boris Johnson should be denied automatic access to parliament for deliberately misleading lawmakers over rule-breaking COVID lockdown parties, a committee said on Thursday in a damning report the former leader described as "rubbish".

In a more than 100-page report, the privileges committee - the main disciplinary body for lawmakers - said Johnson had intentionally misled parliament on several occasions when he was asked about Downing Street gatherings during lockdowns.

The committee also accused Johnson of being "complicit in a campaign of abuse and attempted intimidation".

Its conclusions were a new low for a one of Britain's best-known and divisive politicians who just four years ago led the governing Conservatives to a landslide election victory but whose tenure was cut short by scandal.

Johnson shot back, repeating his innocence and condemning the report as "rubbish", "a lie" and "a charade", and accusing committee members of waging a vendetta against him.

The stand-off will do little to heal the deep divisions in the governing Conservative Party and can only pile pressure on Prime Minister Rishi Sunak, who pledged to restore "integrity, professionalism and accountability" to government.

In the report which details six events held at Downing Street, the committee, which has both members from the governing Conservatives and opposition Labour Party, said: "We conclude that in deliberately misleading the House Mr Johnson committed a serious contempt."

"The contempt was all the more serious because it was committed by the prime minister, the most senior member of the government. There is no precedent for a prime minister having been found to have deliberately misled the House (of Commons, lower house of parliament."

"We recommend that he should not be entitled to a former Member’s pass," it added, referring to a pass which enables former prime minister's to gain access to parliament.

The committee rejected his defence that gatherings were within the rules and that his advisers had supported his belief that was the case.

Instead, it said, Johnson was "deliberately disingenuous when he tried to reinterpret his statements to the House to avoid their plain meaning and reframe the clear impression that he intended to give".

It said that were Johnson still a member of parliament, it would have recommended a suspension from the House for 90 days.

"RUBBISH"

Johnson resigned from parliament last week after seeing an advance copy of the report, calling the inquiry a "witch hunt", a criticism he double-downed on after its publication.

"I believed, correctly, that these events were reasonably necessary for work purposes. We were managing a pandemic," he said in a statement.

"But don't just listen to me. Take it from the Metropolitan Police. The police investigated my role at all of those events. In no case did they find that what I had done was unlawful."

He accused the committee of using mystical powers to see things that he had not seen at Downing Street, when, he said, he was duty bound to thank staff who were departing or for their work on COVID-19. The committee did not accept his defence.

Johnson has apologised for his conduct but repeatedly denied deliberately misleading parliament, saying he took advice from his aides that his office were following the rules.

But so-called partygate ultimately spelled the end for a prime minister, who was mired in scandal. A rebellion in his governing Conservative Party last year forced him in July to say he would step down. He left office in September.

He resigned from parliament last week after a spell as a regular member of the House of Commons, during which he continued to wield significant influence within the Conservatives that at times undermined Rishi Sunak's authority.

While Sunak was once a protege of Johnson, the two have become rivals after Sunak resigned from Johnson's government shortly before it fell. They have also rowed this week over the former prime minister's resignation honours list.

(Reporting by Elizabeth Piper, Alistair Smout, Andrew MacAskill, Kylie MacLellan, Muvija M and William James; Editing by Kate Holton and Frank Jack Daniel)