The chief political commentator of British newspaper the Telegraph has quit over its handling of the HSBC tax avoidance story, calling it a "fraud on readers."

In a lengthy blog post, Peter Oborne castigated the management of the paper, saying it had withheld information about the Swiss bank in order to maintain its advertising account.

Highly critical of the paper's coverage of the HSBC issue since it was broken by BBC's Panorama last week, he wrote, "You needed a microscope to find the Telegraph coverage."

Oborne said that issues with HSBC began in 2012, when the paper began investigating a number of its accounts in Jersey, and accuses the Telegraph of ordering journalists to "destroy all emails, reports and documents related to the HSBC investigation."

In early 2013 the bank suspended its account, and the paper was so eager to regain it (which they did a year later) that stories critical of HSBC were suppressed. He was told by a former executive that it was "the advertiser you literally cannot afford to offend."

His blog post claims a number of stories were pulled from the Telegraph website without good reason, and paints a picture of a paper in thrall to its advertisers, with significant stories like the Hong Kong protests and Tesco's false accounts granted scant coverage due to conflicting financial interests.

Oborne rails against declining standards at the "most important conservative-leaning newspaper in Britain," citing the high turnover of editors and publishing of false stories for online traffic as "inflict[ing] incalculable damage" on the Telegraph.

After five years at the paper, Oborne announced to Telegraph owners Murdoch MacLennan his intention to leave in December. But he said he had a "duty to make all this public," as the Telegraph had failed in its own duty to tell readers the truth:

"It has been placing what it perceives to be the interests of a major international bank above its duty to bring the news to Telegraph readers. There is only one word to describe this situation: terrible."

A Telegraph spokesperson responded to Oborne's blog post:

“Like any other business, we never comment on individual commercial relationships, but our policy is absolutely clear. We aim to provide all our commercial partners with a range of advertising solutions, but the distinction between advertising and our award-winning editorial operation has always been fundamental to our business. We utterly refute any allegation to the contrary.

“It is a matter of huge regret that Peter Oborne, for nearly five years a contributor to the Telegraph, should have launched such an astonishing and unfounded attack, full of inaccuracy and innuendo, on his own paper.”

The blog, which was published last night, arrived ahead of raids this morning on HSBC offices in Switzerland.

It follows a report that the bank turned a blind eye to illegal activities of arms dealers and traders in blood diamonds while helping rich people evade taxes.

Geneva's prosecuters released a statement on the raid:

"Following the recent revelations related to the HSBC Private Bank (Switzerland), the public prosecutor announces the opening of a criminal procedure against the bank... for aggravated money laundering."

"The investigation might be broadened to include physical persons suspected of committing or participating in acts of money laundering," they added.

Oborne spoke to Jon Snow on Channel 4 News last night about his resignation