(AFP) - Boris Johnson on Wednesday apologised for "the pain and the loss and the suffering" caused by the Covid-19 pandemic but defended his government at a public inquiry into its handling of the crisis.

The former UK leader, who has faced a barrage of criticism from ex-aides for alleged indecisiveness and lack of scientific understanding during the pandemic, completed the first of two gruelling days in the witness box.

Johnson -- forced from office last year over Covid lockdown-breaching parties held in Downing Street -- accepted "mistakes" had "unquestionably" been made but repeatedly insisted he and officials did their "level best".

"I understand the feeling of the victims and their families and I'm deeply sorry for the pain and the loss and the suffering to those victims and their families," Johnson said.

"Inevitably we got some things wrong," he added, noting he took personal responsibility for all the decisions made. "At the time I felt... we were doing our best in very difficult circumstances."

The former premier arrived around three hours early for the proceedings, with some suggesting he was eager to avoid relatives of the Covid bereaved, who gathered outside later in the morning.

As he started giving evidence, four women were evicted from the inquiry room after holding up signs stating "the dead can't hear your apologies".

Later, a crowd gathered outside the venue heckled loudly as he left for the day.

- Deleted WhatsApp messages -

Nearly 130,000 people died with Covid in the UK by mid-July 2021, one of the worst official per capita tolls among Western nations.

Johnson, whose lengthy written submission to the inquiry will be published imminently, insisted his government's "overwhelming priority" had been protecting the state-run National Health Service (NHS) and saving lives.

Rejecting statistics that Britain fared worse than European neighbours, he argued "every country struggled" with the outbreak while noting the UK is among the continent's most densely populated and had an "extremely elderly population".

His grilling began with questions about failing to provide about 5,000 WhatsApp messages from late January 2020 to June 2020.

"I don't know the exact reason," he claimed, adding that the app had "somehow" automatically erased its chat history from that period.

Asked if he had initiated a so-called factory reset Johnson said: "I don't remember any such thing".

Inquiry counsel Hugo Keith questioned Johnson about Downing Street chaos during the pandemic, and claims of general incompetence.

Johnson's understanding of specialist advice was doubted last month by his former chief scientific officer, Patrick Vallance, who said he was frequently "bamboozled" by data.

His former top aide Dominic Cummings and communications chief Lee Cain both criticised their ex-boss when they gave evidence at the inquiry.

"What all those comments reflect is the deep anxiety of a group of people doing their level best who cannot see an easy solution and are naturally self-critical and critical of others," Johnson insisted.

- 'Meaningless' -

Keith also quizzed Johnson about everything from shaking hospital patients' hands in early March 2020 to delaying the country's first lockdown for weeks.

"I shouldn't have done that, in retrospect, and I should have been more precautionary," the ex-leader conceded of the hand-shakes, adding he should also have stopped sports events sooner.

He added that the eventual March 23, 2020 lockdown stemmed from "the sudden appreciation" that the virus was more rampant in Britain than previously thought.

"We were clearly wrong in our estimation of where the peak was going to be," Johnson said.

"Once we decided to act, I think it was pretty fast from flash to bang."

Johnson noted that Prime Minister Rishi Sunak, then finance minister, had raised lockdown concerns related to "a risk to the UK bond markets and our ability to raise sovereign debt".

But he said he gave "short shrift" to arguments that lockdowns were too extreme.

"I had no other tool -- literally nothing else," Johnson added, noting that "I couldn't take the gamble with public health".

Sunak will face the inquiry in the coming weeks.

Bereaved families appeared unimpressed by Johnson's apology.

"We've had nearly four years now of rule-breaking, partying, making the wrong decisions," Kathryn Butcher, 59, whose sister-in-law died of Covid, told AFP.

"His apology is meaningless."

© Agence France-Presse