Convoy of the UN Special Envoy to Yemen Martin Griffiths arrives at the airport as he leaves Sanaa, Yemen, Feb. 12, 2019. Griffiths left Yemen's rebel-held capital Sanaa on Tuesday after a one-day visit to push for peace in the war-torn country. (Xinhua/Mohammed Mohammed)

SANAA, Feb. 12 (Xinhua) -- UN Special Envoy to Yemen Martin Griffiths left Yemen's rebel-held capital Sanaa on Tuesday after a one-day visit to push for peace in the war-torn country.

Griffiths will head for Riyadh, the capital city of Saudi Arabia, to meet the exiled Yemeni government of President Abd-Rabbu Mansour Hadi, said an official at the UN mission in Sanaa on condition of anonymity.

It was Griffiths' fourth trip to Sanaa in two months in his attempts to break a stalemate in the implementation of Stockholm Agreement that focused on Yemen's Red sea port city of Hodeidah, the lifeline of the country's most commercial imports and humanitarian aid.

During his Monday's visit, Griffiths warned that grain aid stored in the besieged Hodeidah city to feed over three million people is "at risk of rotting," asking the rival parties to allow the UN team for urgently access to the mills to deliver the aid to the extremely needy.

He said the stores have been inaccessible for over five months and demanded the warring parties for not further delay.

The four-year civil war has pushed over 12 million people to the verge of starvation and created what the UN calls the world's worst humanitarian crisis.

The warring parties reached a peace deal in Stockholm in December last year. They have largely held the cease-fire deal in Hodeidah but failed to withdraw their forces.

The rebels continue to fortify themselves inside the city while the government troops have been massing in the southern and eastern outskirts.

Last week's negotiations led by Michael Anker Lollesgaard, head of the UN cease-fire monitor team in Hodeidah, resulted in what the UN called a "preliminary deal," yet the warring parties showed disputes over it.