Britain's number of deaths "involving" the coronavirus has risen to 46,000, substantially higher than the 36,914 fatalities officially reported so far, according to a statistical update released Tuesday.

The daily death tolls released in Britain only include fatalities that have been confirmed by a positive test. But the Office for National Statistics (ONS) conducts separate studies tallying all fatalities in which COVID-19 is suspected or mentioned on the death certificate.

That figure rose to roughly 46,000 for England, Wales, Northern Ireland and Scotland, although each country reports the number of deaths counted by slightly different dates -- either May 15 or May 20.

This means Britain's virus-related toll is now ever higher, although the weekly trends continue to show a slowdown in the virus's spread.

Countries have struggled to count their dead from the new disease.

Spain took the unusual step Monday of revising down its toll by nearly 2,000 to 26,834.

This happened because Spanish officials switched to a new data gathering system that discovered that some deaths were being counted twice.

But most countries believe that their official toll underreports the real scale of the health disaster.

Italy, which bore the initial brunt of the disease in Europe, discovered in early May that there were nearly 11,700 unaccounted deaths in hospitals, care homes and the community between February 20 and March 31 alone.

If these deaths were added to the official death toll, Italy's number of COVID-19 fatalities would be similar to those reported by the ONS for Britain on Tuesday.

Britain is one of the last European countries to start emerging from its coronavirus lockdown.

Most stores are closed and the few restaurants and cafes that are open only provide takeout and delivery service. But Prime Minister Boris Johnson intends to reopen schools for younger children on June 1, after easing stay at home orders in May.

Non-essential retail will resume on June 15 if the virus remains contained, Johnson said.

Meanwhile, Boris Johnson's government was hit by its first resignation on Tuesday over the controversy surrounding top aide Dominic Cummings' cross-country trip during the coronavirus lockdown.

Undermining attempts by ministers to try and move on from the crisis which has dominated British politics for days, Douglas Ross, a minister for Scotland, quit in protest.

"I have constituents who didn't get to say goodbye to loved ones; families who could not mourn together; people who didn't visit sick relatives because they followed the guidance of the government," he said in a Twitter statement announcing his departure.

"I cannot in good faith tell them they were all wrong and one senior advisor to the government was right."

He added that Cummings' interpretation of government rules was "not shared by the vast majority of people".

The resignation will pile more pressure on Cummings, who held an extraordinary press conference Monday to justify driving his wife and young son on a 264-mile (425-kilometre) trip from London to Durham in the northeast of England during the height of the coronavirus crisis.

- 'Lack of credibility' -
Not long after Ross quit, Harriet Baldwin joined a growing list of Conservative MPs calling on Cummings to resign.

Tory party grandee Michael Heseltine told Sky News that "the lack of credibility" in Cummings' version of events was "damaging the government".

Some members of the clergy have also called on him to stand down as well as opposition party members, who will meet later today regarding the crisis.

Downing Street said it "regrets" the decision by Ross.

The resignation came after a cabinet heavyweight defended Cummings and said the controversial aide did not break the law.

Michael Gove, Chancellor of the Duchy of Lancaster, said Cummings had acted reasonably in driving from London to Durham and then taking a separate journey to a local beauty spot, Barnard Castle, to -- as he claimed -- test his eyesight.

"What's clear is that he didn't break the law, he didn't break the rules, he sought to protect his family and he also sought to ensure that the risk of anyone in his family infecting anyone else was absolutely minimised," Gove told the BBC on Tuesday.

Cummings drove to his parents' home in Durham after feeling ill because he and his wife, who was also feeling unwell, needed possible back-up childcare for their young son.

Despite calls for him to resign, Cummings has so far resisted and instead defended his actions.

He told reporters he had acted "reasonably and legally".

The prime minister called Cummings' actions "plausible".

Also on Tuesday, the Office for National Statistics said the number of deaths in Britain "involving" the coronavirus had risen above 46,000, far higher than the 36,914 deaths officially confirmed in the government's count.