LONDON (Reuters) - British Prime Minister Boris Johnson on Tuesday apologised to parliament for breaking COVID rules with a gathering on his birthday after he was fined by the police last week.

       Johnson and finance minister Rishi Sunak were fined while parliament was on Easter recess. Lawmakers will hold a vote on Thursday on whether Johnson should be investigated over claims he misled parliament by repeatedly saying he had followed COVID rules.

       "I take this opportunity on the first available sitting day to repeat my wholehearted apology to the House (of Commons). As soon as I received the notice, I acknowledged the hurt and the anger, and I said that people had a right to expect better of their Prime Minister," Johnson told lawmakers, adding he had not initially realised the gathering breached COVID rules.

       "It did not occur to me then, or subsequently, that a gathering in the Cabinet Room just before a vital meeting on COVID strategy could amount to a breach of the rules. I repeat that was my mistake, and I apologise for it, unreservedly."

       (Reporting by William James, writing by Alistair Smout; Editing by Kate Holton)