A revived effort to end Yemen’s war under the administration of US President Joe Biden appeared to be faltering on Wednesday when the UN’s envoy to the country said peace talks had hit a roadblock.

The UN Envoy to Yemen, Martin Griffiths, said that a week-long round of talks in Saudi Arabia and Oman involving Mr Biden’s envoy to Yemen, Tim Lenderking, had failed to make progress, as a Houthi rebel offensive on the government-held city of Marib continued.

“We have been discussing these issues for over a year now,” Mr Griffiths said.

“The international community has been supporting us in full force. Unfortunately, we are not where we would like to be in reaching a deal. Meanwhile, the war has continued unabated, causing immense suffering to the civilian population.”

Since taking office in January, the Biden administration has sought to bring an end to Yemen’s conflict by withdrawing support for offensive operations by the Saudi-led coalition that is battling Yemen’s Iran-aligned Houthi rebels.

Riyadh responded by announcing a peace plan in March, which would see blockades on the country lifted and a UN-supervised ceasefire between the Saudi-backed government and the Houthis, who control the capital Sanaa and much of the north.

This week’s negotiations involving Mr Griffiths and Mr Lenderking were aimed at advancing that ceasefire, but are understood to have been complicated by the Houthi assault on gas-rich Marib, the government’s last northern stronghold.

Analysts say the conflict is also enmeshed in broader tension between Saudi Arabia and Iran amid the Biden administration’s efforts to revive an international deal restricting Tehran’s nuclear programme.

“I will keep engaging the parties to the conflict and all involved and concerned actors and stakeholders to offer them opportunities to find common grounds to help advance the peace efforts,” said Mr Griffiths.