LONDON, April 21 (Reuters) - British Deputy Prime Minister and justice minister Dominic Raab resigned on Friday, following an independent investigation into formal complaints of bullying.

In a letter to Prime Minister Rishi Sunak published on Twitter, Raab said the inquiry had set a dangerous precedent, but that he would remain supportive of the government.

"I called for the inquiry and undertook to resign, if it made any finding of bullying whatsoever. I believe it is important to keep my word," Raab said.

However, he added: "In setting the threshold for bullying so low, this inquiry has set a dangerous precedent. It will encourage spurious complaints against Ministers, and have a chilling effect on those driving change on behalf of your government - and ultimately the British people."

Raab's resignation means a third senior minister has departed over their personal conduct since Sunak entered Downing Street in October promising a government of integrity.