This Monday, Defence Secretary Michael Fallon was obliged to tell MPs that British-made cluster bombs had indeed been dropped on Yemen by Saudi Arabia.

Dunne's misleading assertion about cluster bombs is just the latest in a long series of inaccurate written and oral statements to parliament made by British ministers.

The culprits include Philip Hammond, before he was moved from the Foreign Office to the Treasury in the wake of Brexit. Hammond said in February that Britain had "assessed" that there had not been any breach of international humanitarian law in Yemen by the Saudi-led coalition.

However, when Boris Johnson became Foreign Secretary in July, he immediately ordered his predecessor's untrue statement to be corrected. In a humbling moment for Hammond, the Foreign Office put out a statement which made clear his remark had been false. No assessment of any kind had been carried out.

READ: UK government admits it has not assessed alleged Saudi war crimes

There is, therefore, no question that Philip Hammond (and others including the current Middle East minister Tobias Ellwood) systematically misled the House of Commons on Yemen.

The effect of their statements was to protect Saudi Arabia as it led a murderous series of bombing raids which have wiped out weddings, attacked hospitals, funerals, markets and homes, in the process killing thousands of people. As I learned for myself in the Yemen, these tactics are ensuring that many there now hate our country for backing the Saudis.

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It is important to remember that misleading the House of Commons is always one of the most serious offenses which any minister can commit - and all the more so when it concerns a matter of life and death.

The Ministerial Code of Conduct is completely unambiguous on this point. It commits ministers to giving "accurate and truthful information to Parliament". Any government minister who misleads the House of Commons is under a duty to return to the House and correct any false statement at the first opportunity.

And if ministers deliberately mislead the House, they must resign because they can no longer be trusted to occupy their office.

The false statements put out by ministers to parliament about the British assessment of the carnage being carried out by the Saudi-led coalition bombers on the Yemen were therefore a deadly serious matter.

That is why I am very puzzled why the government has not treated the matter seriously at all. Shockingly, there has been no apology. Shamingly, the corrections in July, which can be read here, were quietly shuffled out on the final day before the summer recess.

And crucially, there appears to have been no investigation into how ministers repeatedly came to mislead the Commons - and no rebuke for those responsible.

This is truly shocking. For any government department with high standards of integrity, it should have been a matter of urgent importance to understand how MPs and the nation were misled, and what went wrong.

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That is why last autumn, I rang the Foreign Office press office to ask whether there had been an inquiry and, secondly, whether any disciplinary action had been taken against those responsible.

A press officer said that the matter was already the subject of a freedom of information request. She asked me to wait until the FOI request had been answered, stating that I would then be able to discover the truth about what happened. I agreed to her request out of good nature, and now regret doing so.

That FOI request, which was finally answered last week after a lapse of more than two months, can be found here.

The documents published contain no reference of any kind to a Foreign Office inquiry into how ministers came to mislead parliament, nor is there any reference to subsequent disciplinary action.

So I got back in touch with the press spokesperson, saying that I felt that she had led me up the garden path. I then put the questions to her again: had there been an investigation into how ministers misled parliament, and had anyone been disciplined as a result. I have received no answer to either question.

I can only reach one conclusion from my dealings with the Foreign Office over this very serious matter: there has been no inquiry as to how MPs came to be misled, and there have been no consequences of any kind for those responsible.

The failure to launch an inquiry would be extremely troubling in any circumstances. It is nothing short of repugnant when it involves Yemen, a country on the verge of famine and where thousands have been killed by bombers from the Saudi-led coalition.

I saw for myself the horror ordinary Yemenis are experiencing when I visited the country last July. The hospitals cannot access left-saving medicines. Millions are on the edge of starvation. Millions more have fled their homes. Innocent people are being killed by air strikes. All this in a country where Britain has intimate links dating back 300 years.

The most generous construction on the failure to hold an inquiry is that there is an insouciant and careless culture in the Middle East section of the Foreign Office. Ministers feel they can utter untruths regardless of the consequences, their statements are purely weightless, and part of a post-truth environment where government statements have no connection with any underlying reality.

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There is, however, a very sinister alternative explanation: ministers were deliberately lying in order to cover up the truth about what they knew about the carnage being inflicted on the people of the Yemen by the Saudi-led coalition. There was no inquiry, and no punishment, because nobody had done anything wrong. Perhaps because ministers were following orders.

If that is so, Hammond's statement to MPs last February was not a mistake. It was part of a deliberate attempt to deceive them in order to cover up mass murder carried out by British allies in one of the ugliest conflicts in the world. If that is so, Hammond (and his ministerial colleagues) have got blood on his hands. He has deceived the Commons over a matter of life and death.

Was Hammond's statement a simple mistake or a deliberate lie? Readers must make up their own minds.

Once again, I urge the Foreign Office to answer the questions I have been putting to it since the autumn. Has there been an inquiry into how Hammond and fellow ministers came to mislead parliament over the British "assessment" of Saudi breaches of international humanitarian law?

Secondly, if such an inquiry did take place, was anyone disciplined? It is essential that ministers come up with an answer. Otherwise British ministers will never again be trusted when they speak out on the subject of this terrible conflict. 

- Peter Oborne was named freelancer of the year 2016 by the Online Media Awards for an article he wrote for Middle East Eye. He was British Press Awards Columnist of the Year 2013. He resigned as chief political columnist of the Daily Telegraph in 2015.