With Johnson embroiled in a scandal after promising Dyson that his staff wouldn’t pay extra taxes if they returned to the UK to help make ventilators amid the coronavirus pandemic, his spokesman told reporters on Thursday that an investigation has been launched into the leak.

“I can confirm that, yes, we have instructed the Cabinet Office to look into this,” he said, adding that it would be an “internal inquiry.”

The investigation will “get into the source of leaks of private communication” between the PM and Dyson and “is limited to that.”

Unnamed sources close to the prime minister told The Guardian that Johnson is “constantly lobbied by phone,” where discussions are private unlike official meetings, and that the habit had become a growing concern.

The newspaper reported this week that Johnson “has had the same number for a decade,” has given his phone number out “liberally” over the years and is “regularly texted by business leaders and politicians” as “only meetings and not text messages need to be disclosed.”

On Wednesday, however, amid public outcry, Johnson refused to apologise for the under-the-table text messages and promised to publish his discussions with Dyson.

“I make absolutely no apology at all for shifting heaven and earth and doing everything I possibly could, as any prime minister would in those circumstances, to secure ventilators for the people in this country and to save lives,” he declared, claiming there is “absolutely nothing to conceal.”

Earlier, Labour leader Keir Starmer accused the government of “sleaze, sleaze, sleaze” and said the leaks demonstrated a culture of “favours, privileged access, tax breaks for mates.”

A committee of MPs are reportedly discussing whether to interrogate Johnson over his private mobile phone use.