The United Nations has “regained optimism” for peace in Yemen after recent progress towards creating conditions for a political process to end the civil war, special envoy Martin Griffiths told The National.

“We have seen recently small signs of hope in an overall devastating war,” Mr Griffiths said in an exclusive interview.

"Reduction of violence in the north, release of a limited number of prisoners and detainees, permission of fuel ships to enter in Hodeidah, humanitarian access in the city of Al Duraihimi, establishment of joint observation posts in Hodeidah are some of these positive signs that encourage us to continue our work with regained optimism.”

Yemen’s government and the Houthi rebels agreed to a series of confidence-building measures at talks in Stockholm last December, including a ceasefire in the port city of Hodeidah and a prisoner exchange. The agreement was seen as the first significant breakthrough in UN-led efforts to end more than four years of conflict but its implementation has been delayed by mutual distrust.

“It is true that progress has been slow but this should neither deter us nor distract our attention from our main goal, which is the political process,” Mr Griffiths said.

He believes that both sides are “currently on a good path and have presented tangible progress”.

“What the parties showed us last year in Sweden is that they can find common ground. Our role is to help them build upon this common ground and identify more areas of convergence,” he said.

The UN envoy said talks were under way to free more detainees.

“I am confident that we will see similar initiatives soon and this confidence is based on what I hear from the parties,” he said.

“If we look at similar cases around the world, we see that exchange of prisoners is difficult during an active conflict,” he said, and Yemen “is no different in this regard.”

Mr Griffiths said the setting up of joint observation posts in Hodeidah was “remarkable and tangible progress”.

“It shows that the level of trust has increased between the two parties and it further shows that the agreement has been working as a confidence-building measure.”

Humanitarian officials have long pleaded with Yemen’s warring sides to spare Hodeidah, the main entry point for food and aid in a country where more than 14 million people, or half the population, are dependent on the World Food Programme’s biggest operation to survive.

Mr Griffiths said he was hopeful that the implementation of the Hodeidah agreement “will regain momentum and the parties will overcome the rest of their differences”.

“The time frame, though, for a formal process will depend on the political readiness of the parties,” he said.

The UN envoy also hailed the power-sharing deal between the government and southern secessionists as a “significant contribution” towards paving the way for wider peace talks.

President Abdrabu Mansur Hadi and Aidarous Al Zoubaidi, the leader of the Southern Transitional Council (STC), are expected to sign the agreement at a ceremony in the Saudi capital Riyadh on Sunday.

“I hope it will be implemented without delay and that it will strengthen the functioning of state institutions in Aden and the delivery of basic services to the people,” Mr Griffiths said.

Mr Hadi’s government moved base to the southern port city after the Iran-backed Houthi rebels seized the capital, Sanaa, in 2014.

The government and the STC have been allies in the fight against the rebels. However, clashes broke out between their forces in August over political differences, including the future status of the south and the STC’s demand to be part of international peace negotiations.

The two sides resolved their differences in talks mediated by Saudi Arabia, which leads a military coalition that intervened in Yemen’s war on the government’s behalf in 2015.

Mr Griffiths said he had always pushed for the inclusion of southern voices in Yemen’s political process.

“I hope that this agreement will have a positive impact in my efforts to mediate an inclusive peace process,” he said.

The UN envoy praised Saudi Arabia for its “extraordinary job and strenuous efforts in mediating successfully these talks.”

“And I am also thankful for the Coalition’s commitment, including the United Arab Emirates, to oversee and support the implementation of the agreement,” he said.