Banking giant HSBC may be attempting to suppress free speech by pulling advertisements from newspapers that publish negative stories about it, ex-Daily Telegraph journalist Peter Oborne has claimed.

Mr Oborne, who said last night that he had quit as the Telegraph's chief political commentator over the issue, has accused his former paper of downplaying stories about HSBC because it is a major advertiser and he said the bank has "big questions to answer".

In an article for the website Open Democracy, Mr Oborne said the newspaper did not give sufficient coverage to allegations that the bank was promoting tax avoidance schemes.

In response, the Telegraph said it utterly rejected Mr Oborne's claims, which it said were full of inaccuracies.

Mr Oborne repeated his claims today, telling BBC Radio 4's Today programme: "There has been a series of stories which look very much as if poor editorial judgment has been exercised and they tend to affect significant advertisers."

He claimed he had raised his concerns with management but "they didn't show any interest in my questions and I resigned from the paper but I just said I'd go quietly".

He went on: " But last week was such a terrible example of this - BBC Panorama's investigation into HSBC's Swiss banking arm was just not really covered in the Telegraph..."

The Guardian has alleged that HSBC put its advertising account with the newspaper "on pause" as negotiations were continuing over last week's series of stories about the Swiss banking arm.

Mr Oborne said it looked as though the bank was using advertising to suppress free speech.

He said: "HSBC did the same thing with the Telegraph. There's a pattern developing here that when HSBC was being investigated, the advertising dries up.

"It looks to an outsider very much as if it is using advertising as a tool to suppress free speech.

"They need to explain why they suspended their advertising in the Guardian last week and in the Telegraph for a year."

In his Open Democracy article, Mr Oborne claimed the Telegraph suppressed stories about HSBC from the start of 2013 onwards after its investigation team published a series of articles about the bank's accounts in Jersey in late 2012.

He said HSBC suspended advertising with the Telegraph and the reporters involved in the investigation were asked to destroy all material relating to it.

He went on: "This was the pivotal moment. From the start of 2013 onwards, stories critical of HSBC were discouraged."

Mr Oborne said that after a year the HSBC advertising account was restored but since then stories critical of the bank have received minor coverage when compared with other news outlets.

In a response to Mr Oborne's article, the Telegraph said: "Your questions are full of inaccuracies, and we do not therefore intend to respond to them.

"More generally, 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."

HSBC refused to comment on Mr Oborne's remarks.

Mr Oborne also called for an independent review of the Telegraph's editorial guidelines.

He told the Today programme: "They put out a statement yesterday saying that my article was basically a tissue of lies, that there were no breaches between the advertising and the editorial.

"If that is so, they need to come out and explain what were the editorial guidelines being used which justified that HSBC story."

He added: "The Telegraph must now call an independent review."