UN Special Envoy to Yemen Hans Grundberg visited Sanaa on Monday for the first time since he took over the post seven months ago.
Mr Grundberg is scheduled to meet Houthi leaders after a truce that took effect on April 2.
The aim of the visit is to engage with the Houthi leadership on "implementing and strengthening the truce and discussing the way forward," the envoy's office said in a statement.
The visit came as the two-month truce entered its second week with reports of violations particularly around the central city of Marib. Last week, the UN envoy urged the warring sides to uphold the truce.
Yemen’s internationally recognised government has accused the Iran-backed Houthis of attacking their positions in southern and western Marib.
A Houthi spokesman was not available for comment. Houthi-run media, however, accused government forces of violating the truce in Hodeida, the key rebel-held port city.
Mr Grundberg had met repeatedly with chief Houthi negotiator Mohammed Abdul Salam in Oman’s capital of Muscat, most recently on Sunday.
The visit was apparently facilitated by Oman, which has played a mediation role in Yemen’s war.
Mr Grundberg also met Sunday with Omani Foreign Minister Sayyid Badr Albusaidi before leaving Muscat for Sanaa, the Omani Foreign Ministry said.
"The UN envoy will discuss in Sanaa the requirements for a comprehensive settlement in Yemen," the ministry said.
Although Mr Grundberg has been in the position for under a year, major positive steps have been taken on issues including the stricken tanker FSO Safer, the fuel crisis and peace efforts.
Fuel ships have already begun entering the port of rebel-held Hodeidah while the long awaited reopening of Sanaa airport remains highly anticipated.
As part of the ceasefire, Mr Grundberg said he has invited Yemen's warring sides to convene a meeting to agree on a reopening of roads around the province of Taiz and other provinces as part of the truce.
The war in Yemen has spawned one of the world’s worst humanitarian crisis, leaving millions suffering from food and medical shortages. It has killed over 150,000 people, including fighters and civilians, according to a database project that tracks violence.
The truce has brought some relief for Yemenis during the Muslim holy month of Ramadan, which started earlier in April.
