Boris maintains radio silence on Iran crisis: Johnson faces being plunged into tense stand-off as his allies say Jeremy Hunt must 'take responsibility' for blunders over seized tanker

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Boris Johnson faces being plunged into the escalating Iran crisis - as allies insisted Jeremy Hunt must 'take responsibility' for blunders.

The Tory front runner is set for a baptism of fire as he prepares to take over from Theresa May this week, as tensions rise with Tehran.

The government has been accused of 'dropping the ball' by failing to protect UK-flagged shipping in the Strait of Hormuz, after a tanker was seized by Iranian forces.

In a blunt message today US secretary of state said it was down to Britain to 'take care of their own ships'.

Critics have pointed out that Mr Johnson's record of dealing with Iran is not good, after he was accused of extending Nazanin Zarghari-Ratcliffe's stay in prison by suggesting she was not on holiday in the country when she was arrested over spying allegations. 

In a sign that Mr Johnson could opt to make his Tory leadership rival Mr Hunt the fall guy for the situation, Jacob Rees-Mogg said it would be 'vanity' if the current Foreign Secretary refused to accept a demotion.

Boris Johnson (pictured in London today) is set for a baptism of fire as he prepares to take over from Theresa May this week, as tensions rise with Tehran

Mr Johnson could opt to make his Tory leadership rival Jeremy Hunt (pictured in Downing Street today) the fall guy for the Iran crisis after allies said he must 'take responsibility' for mistakes in handling the situation 

The UK-flagged Imepero being watched over by an armed Iranian vessel at the port of Bandar Abbas, where it is being held after it was seized in the Strait of Hormuz on Friday last week

Iran seized the British-flagged Stena Impero last week in retaliation after its own vessel, the Grace 1, was stopped by Royal Marines off the coast of Gibraltar last month. 

Iran says the operation was 'piracy' carried out on behalf of the US, while Britain says the ship was violating EU sanctions.

Questions have been raised over why the Royal Navy was not on hand to protect the vessel in one of the most crucial shipping routes in the world. 

The stand-off comes amid growing friction over the Iran nuclear deal, after Donald Trump unilaterally withdrew US support.

European nations including the UK have pledged to stand by the pact despite the threat of American sanctions on business.  

But Iran has now openly breached the terms in revenge for the US action, with the situation threatening to spiral into a 'hot' conflict. 

Mr Johnson is the favourite to win the Tory leadership race and take over from Theresa May on Wednesday.

Some allies have indicated that if he achieves a comfortable victory over Mr Hunt he would be prepared to demote his rival - effectively sacking him as he be unlikely to accept a more junior post.

An iranian armed guard is seen patrolling along the deck of the Imepero in the latest taunt to Britain. Iran is trying to secure the release of its tanker - the Grace 1 - which was seized by Royal Marines near Gibraltar earlier this month

Mr Rees-Mogg (pictured in London today) said Mr Hunt should be prepared to accept a lesser role in order to preserve party unity

However others have claimed the pair will 'kiss and make up' despite tetchy clashes during the contest. 

Mr Rees-Mogg said Mr Hunt should be prepared to accept a lesser role in order to preserve party unity.

He said Mr Hunt did not have a 'claim to a specific office' in a government led by Mr Johnson.

The prominent Eurosceptic told LBC Radio: 'I think that Jeremy Hunt should accept whatever he is offered. Previously Jeremy Hunt has indicated that he will only serve in the highest offices - I think that's a vanity.

'I think people have to rally round, support the country and the party, and accept the new leader.

'Grandstanding and saying 'if I'm not Foreign Secretary I won't be anything' is not the right approach to take.'

In a thinly-veiled attack on Mr Hunt's record, he added: 'It's bad luck that just as this is all being considered there is a problem of a very serious kind with Iran which the Foreign Office must take some responsibility for.

'I think it's too early to say whether Jeremy Hunt will be counted among the greats in that office.'

Sir Alan Duncan - a long-time foe of Mr Johnson - announced his resignation as the Foreign Office number two today on the eve of the new Tory leader being installed.

In his letter, Sir Alan sniped that he was frustrated at working under the 'dark cloud of Brexit' - and also took aim at Mr Johnson's handling of the case of Nazanin Zaghari-Ratcliffe.

As Foreign Secretary, Mr Johnson notoriously slipped by telling a Commons committee that Mrs Zaghari-Ratcliffe was teaching journalism in Iran, rather than holidaying there.

Keeping watch: An Iranian Revolutionary Guard patrol boat sails in front of the Stena Impero, the UK-flagged vessel which was seized by Iranian authorities on Friday 

The gaffe was seized on by the Tehran authorities to back up their claim that she was spying - something she and the UK has always furiously denied.

Her sentence was said to have been extended as a direct result, and she is still serving time in Iran. 

Frigate HMS Montrose is on duty in the Gulf but was unable to prevent the seizure of the Stena Impero.

Defence Minister Tobias Ellwood, speaking on ITV's Good Morning Britain, said: 'There is much criticism about the Navy, about HMS Montrose not getting to there on time - I should actually point out that the USA have five or six warships in the region, including an aircraft carrier, and in the middle of June two of their tankers were attacked, one of them set ablaze.

'So, this is something that affects us all, it requires international co-operation, but also, most importantly, recognition that there's a bigger geostrategic challenge facing (us) here - that is the reason why Iran is doing those things.'

Mr Ellwood continued his calls for more funding and investment for the armed forces in the face of more 'diverse and complex threats' and said the Iranian issue is an example.

Retired commander of UK maritime forces Rear Admiral Alex Burton said cuts to the Royal Navy's fleet had limited its ability to act.

'There is no doubt that the size of the Navy since 2005 - reduced from 31 frigates and destroyers to now 19 - has had an impact on our ability to protect our interests around the globe,' he told BBC Radio 4's Today programme.

'I credit the politicians for acknowledging this now but it should have been acknowledged and pressed earlier.'

Chancellor Philip Hammond's parliamentary aide, Huw Merriman, told Today that the Government has 'dropped the ball' over the situation.

He said: 'We did not put in place a chain where we asked all of our vessels to leave at a certain time under convoy, so it was hardly a surprise when one of ours got taken.'