Jeremy Hunt warns that a humanitarian disaster is on Yemen's doorstep as he visits war-torn country

Foreign Secretary Jeremy Hunt has become the first senior Western politician to visit Yemen since the country collapsed into a vicious and unrelenting civil war four years ago that has led to what the UN and most aid agencies describe as one of the worst, if not the worst, humanitarian crises in the world.

Amidst tight security, Mr Hunt flew into the southern port city of Aden, which is the base for the internationally-recognised Yemeni government fighting the Houthi rebel insurgency that controls the capital, Sana'a.

Despite a severe security situation, the Foreign Secretary said that he wanted to make the journey to deliver a very clear and unmistakable message, in person, to all sides in the conflict.

Jeremy Hunt said it was imperative for all sides to observe the 'Stockholm Process'.

He said the situation was at a critical and potentially decisive moment.

Failure to implement the so-called "Stockholm Process", an agreement on the re-deployment of Houthi and government forces which should open up access to humanitarian supplies and routes (especially in the Houthi-controlled port city of Hodeidah), would very quickly lead to a humanitarian catastrophe that would be very hard to come back from.

Speaking exclusively to ITV News in Aden, Mr Hunt said he had delivered "difficult" messages to the Yemeni government and their regional allies - Saudi Arabia and the United Arab Emirates - but also to the Houthi rebels, whose chief spokesman, Mohamed Abdul Salam, he'd met recently in Oman.

Many routes have been blocked, meaning humanitarian aid cannot be accessed.

The UK is part of the Saudi-led international coalition supporting the Yemeni government of President Hadi.

Mr Hunt, however, rejected criticism that this made the UK a biased voice in the process to find a way out of the devastating four-year conflict that has seen hundreds of thousands of Yemeni children suffer and die from malnutrition and cholera.

He said the fact that the UK was able to bring all sides together, and that the UK was currently chairing UN oversight of Yemen, gave it a unique position where it was able to convene all parties to a process of halting the fighting in order to address, what he acknowledged, was a catastrophic situation for Yemeni civilians.

Thousands of Yemeni children have already died during the war.

Asked by ITV News whether criticism of continued UK arms sales to Saudi Arabia and the United Arab Emirates undermined this role, Mr Hunt said that it was due to the UK's strategic relationship with Riyadh and Abu Dhabi that it was able to carry messages which carried real weight.

Mr Hunt ended by saying that everyone needed to realise that this was the last chance for peace in Yemen, and that if the "Stockholm Process" was allowed to fall apart by neglect, it was hard to see how any similar kind of pause in the fighting and the suffering could be achieved.

Mr Hunt warned that a catastrophe was looming.