Boris Johnson has spoken of his “humility” as he addressed MPs for the first time since receiving a fixed-penalty notice for breaching lockdown rules.

The prime minister repeated the apology he gave for his conduct in the wake of last week’s fine, but urged MPs to focus instead on pressing issues including the conflict in Ukraine.

Johnson said he had just been discussing Ukraine with world leaders including Joe Biden, but first wanted to address MPs “with all humility”. His apology went on for just under two minutes and included his defence that he believed it did not break the rules.

“I paid the fine immediately, and I offered the British public a full apology,” he said. “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 – and I repeat that again in the house now.”

He added: “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. That was my mistake and I apologise for it unreservedly.”

Johnson said the “hurt and anger” prompted by his lockdown behaviour had given him “an even greater sense of obligation to deliver on the priorities of the British people, and to respond in the best traditions of our country to Putin’s barbaric onslaught on Ukraine”.

Responding to Johnson’s statement, the Labour leader, Sir Keir Starmer, said: “What a joke. Even now, as the latest mealy-mouthed apology stumbles out of one side of his mouth, a new set of deflections and distortions pours from the other.”