How easily the West allows itself to be repeatedly duped by the religious rulers of Iran.

Past masters at the art of deception, they have defied world opinion for the past decade in their race to build nuclear weapons, but after eight tortuous years of confrontation with the unstable Mahmoud Ahmadinejad at the helm, Supreme Leader Ali Khamenei must have finally realised that the only way to buy more time was to convince the west that a moderate had emerged as the new president of Iran.

The emergence of the cleric Hassan Rouhani, following the recent presidential elections in Iran, seemingly ticked all of the boxes. The western press pointed to his PhD from Glasgow Caledonian University and crowed that this new "moderate" president would be open to dialogue on stopping Iran's nuclear programme and told us that his election would bring about positive change for the oppressed masses in Iran.

However, it an open secret that presidential elections in Iran are merely reshuffles amongst the ruling circle. Mr Rouhani emerged from a list of eight hand-picked candidates, who were variously advisers, aides, or representatives of Mr Khamenei. Mr Rouhani has in fact been part of the establishment for decades. He held the position of secretary of the Supreme National Security Council for 16 years, was a member of the powerful Expediency Council and was Mr Khamenei's representative in the Supreme National Security Council.

Mr Rouhani's likely role now is to further the mullahs' nuclear ambitions. In a reminder of just how far along these plans are, the Paris-based National Council of Resistance in Iran (NCRI) this month released evidence to the west of a new secret underground nuclear facility being carved into a mountain 45 miles north-east of Tehran. Despite this startling revelation about Iran's nuclear programme, western leaders would still rather believe they can convince Iran to put a halt to its nuclear agenda.

Even now some senior members of the House of Lords are still urging the Government to restore full diplomatic relations with Iran because "the new president has made clear his commitment to greater transparency on nuclear matters and more freedom for Iran's people and press". The sheer absurdity of such a suggestion – made by Baroness Williams of Crosby, Lord Lamont of Lerwick and Lord Phillips of Sudbury in a recent letter to The Times – in light of recent developments, is breath-taking.

Some international experts believe that in as little as one year from now the Iranian regime may have enough weapons-grade uranium to build a nuclear missile. By wooing Mr Rouhani under the pretext of hopeful rapprochement, Western leaders are taking their eye off the nuclear ball, with potentially terrifying consequences for the Middle East.

The good news is that the political class in Iran is not exactly in a state of rude health. As economic sanctions have brought the country to its knees, it is a regime on the brink. Their continued survival is based on the notion of the absolute rule of the Supreme Leader, requiring the maintenance of an atmosphere of fear and terror, seen most vividly with scores of hangings in recent weeks, many of them taking place in full public view.

The notion that we can now deal with a "moderate" Iranian presidency, however, will simply play into the hands of the mullahs, allow the country to advance its nuclear programme and prolong the agony of the Iranian people. We cannot afford to dither while all this goes on.

Contrary to what Western leaders believe, it is not the election of Mr Rouhani but the departure of the mullahs that will actually guarantee peace, democracy and freedom in Iran.

Struan Stevenson is a Scottish Conservative Euro MP for Scotland and is President of the European Parliament's delegation for Relations with Iraq.