The UN envoy to Yemen Martin Griffiths arrived in Yemen's rebel-held capital Sanaa on Thursday in an attempt to calm down tension as fighting near the capital threatens to fail the peace process.

Griffiths will hold discussions with officials from the Houthi rebel group in Sanaa over the recent military escalation and push for resuming the peace process that has been stalled since the Yemeni warring parties reached a cease-fire agreement in Stockholm in December 2018.

In a statement on Wednesday, Griffiths called on all Yemeni parties to "cease all military activities including movement of troops, airstrikes, as well as missile and drone attacks."

"We all have to work toward advancing the peace process, not setting it backward. Yemen has suffered enough," Griffiths said in the statement.

The clashes and airstrikes have escalated on several fronts in Nehm distrcit of Sanaa following last week's missile attack in adjacent Marib Province which was blamed on the Houthi rebels.

The clashes in Nehm, some 60 km northeast of Sanaa, have killed scores from both sides as the government forces are pushing toward Sanaa, according to pro-government news website al-Masdar Online.

Yemen has been mired in a civil war since late 2014, when the Iran-backed Houthi rebels seized control of much of the country's north and forced the Saudi-backed government of President Abd-Rabbu Mansour Hadi out of Sanaa.