Boris Johnson has earned at least £2.7 million for columns in The Daily Telegraph newspaper during his time as an elected politician.

The current frontrunner to succeed Theresa May as prime minister has been paid variable sums by the Telegraph since he first became an MP in 2001, a HuffPost UK analysis found.

Johnson, 54, was initially paid at least £25,000 a year for a column in the Telegraph’s pages, with his current salary now £275,000. His total pay was £2,747,103, including his expected earnings for the current year, according to official records.

The subject of Johnson’s paid work for the Telegraph was debated on Thursday after the newspaper supported the MP’s bid to become Tory party leader alongside a gushing editorial on its front page.

Johnson, the Telegraph said, “brings not only experience to the contest but an infectious optimism”.

The paper’s coverage was criticised on Thursday with the Labour deputy leader, Tom Watson, writing on Twitter: “Now is the time to remember Boris Johnson gets paid £5,200 a week by The Daily Telegraph.”

“Translate that [front page] into Turkish and you have Erdogan’s idea of what a front page should look like,” the Guardian journalist Jonathan Freedland said of the front page, in reference to Turkey’s authoritarian leader.

Both Johnson and The Daily Telegraph have been approached for comment.

HuffPost UK calculated Johnson’s minimum earnings from the Telegraph using a combination of official registers of interest and published tax returns for him as MP for Henley, Mayor of London, and MP for Uxbridge and South Ruislip.

He gave up his Telegraph job in July 2016 when appointed foreign secretary, but went back to writing for the broadsheet after he resigned last July.

The first record of Johnson’s salary for the Telegraph job appeared in a November 2002 edition of the House of Commons Register of Members’ Interests.

His salary was stated at the time as being between £25,001 and £30,000. HuffPost UK used the lowest figure for its calculation.

By December 2005, Johnson declared his salary from the Telegraph was between £70,001 and £75,000.

But by May 2007, his declaration noted his salary was between £245,001 and £250,000.

Johnson published his tax returns during his campaign to stay on as Conservative mayor of London for a second term in 2012, which showed he earned £250,000 for his Telegraph column between 2008 and that year.

A subsequent tax return, dated April 2016, shows he continued to earn a salary of between £220,430 and £266,667 between the 2011/12 and 2014/15 financial years.

Once he returned to parliament as MP for Uxbridge and South Ruislip in 2015, Johnson declared income of £22,916.66 a month – or £275,000 a year – from his job at the Telegraph.

His register of interests shows payments from the Telegraph stopped in July 2016 after Johnson joined the government, but they resumed on the same terms upon his resignation two years later.

Johnson’s current Telegraph contract runs until July 2019, according to his latest Commons declaration of interests.

Johnson earns a £79,000 salary as an MP and his role as foreign secretary provided an additional £60,000. Johnson earned £143,911 a year in his second term as mayor of London between 2012 and 2016.

Prior to his political career, Johnson worked for the Telegraph variously as a leader writer, Brussels correspondent, political commentator and assistant editor.